Maritime Cyber Resilience Brief ③ — Bridging IACS and USCG Cyber Rules

Part 3 — Bridging IACS and USCG Cyber Rules: Alignment, Gaps, and Synergies

With IACS UR E26/E27 now shaping newbuild vessel design worldwide and the USCG Cybersecurity Rule imposing operational cyber standards in the U.S., maritime stakeholders naturally ask: How do these regimes intersect? This part explores the technical and regulatory interoperability between IACS’s approach and the Coast Guard’s requirements. We highlight areas of strong alignment (where compliance with one inherently aids compliance with the other) and identify residual gaps (where one framework demands something the other does not). Finally, we discuss how adopting E26/E27 can mitigate compliance risks under the USCG rule, using illustrative examples. The encouraging news for ship owners and operators is that there is considerable common ground — both frameworks promote a risk-based, resilience-focused philosophy — but there are also important differences in scope and emphasis that need attention.

Common Foundations and Alignment Areas

It is no coincidence that the IACS and USCG cybersecurity initiatives share many common elements. IACS’s UR E26/E27 were developed with reference to international standards like NIST and IEC 62443, which also informed the USCG’s approach. In fact, ABS (a leading class society) explicitly recommended the Coast Guard align its new regulations with IACS UR E26/E27 to avoid duplication and maximize global consistency. At a high level, both the class requirements and the USCG rule seek to implement a cybersecurity risk management framework centered on Identify, Protect, Detect, Respond, Recover — ensuring maritime systems can withstand and bounce back from cyber incidents. Here are key alignment areas:

• Risk Management Framework: Both frameworks utilize the five-function model. UR E26 is literally structured around Identify/Protect/Detect/Respond/Recover, and the USCG rule’s requirements can be mapped to the same functions (e.g. asset inventory = Identify; segmentation and patching = Protect; monitoring = Detect; incident response plans = Respond; backups = Recover. The Coast Guard’s stated goal is to help operators detect, respond to, and recover from cyber incidents affecting the MTS, which resonates with IACS’s resilience goals for vessel safety. Thus, a company that has implemented the NIST framework for E26/E27 will find a familiar structure in organizing the USCG-mandated plan.
• Asset Inventory and Risk Assessment: Both IACS and USCG approaches start with knowing what you have. E26 mandates a vessel asset inventory of onboard OT systems and networks. The USCG rule similarly requires a cybersecurity assessment identifying all IT/OT systems and evaluating their vulnerabilities and criticality. If a new ship was built under E26, it comes with a documented inventory and initial risk assessment (including identification of essential systems and their interconnections) — that provides an excellent foundation for the broader facility or vessel assessment required by USCG. Essentially, both demand you “Identify” your digital assets and understand the risks.
• Network Segmentation and Zones: This is a standout common requirement. UR E26 requires security zones and conduit protections to isolate critical functions. Likewise, the USCG rule expects network segmentation to be implemented to protect mission-critical systems. In practice, a vessel designed to E26 will have physically or logically separate networks (e.g., separating navigation, engineering, and crew networks) with firewall rules controlling any data flow between them. This directly satisfies the Coast Guard’s expectation that, say, a malware infection on a crew laptop should not easily propagate to the engine control system. If an inspector asks how you isolate critical systems, an E26-compliant ship can show its class-approved network diagram with defined zones — a clear alignment in technical control.
• Access Control and Authentication: Both frameworks emphasize controlling access to systems. E26/E27 include requirements for access control, user authentication, and management of credentials on onboard systems (with allowances for some exceptions). The USCG rule requires measures like multi-factor authentication and strict user access management for critical system access and remote connections. A newbuild that met E27 will, for example, have eliminated shared default passwords on equipment and implemented role-based accounts, which directly helps meet USCG’s expectations for secure system access.
• Monitoring and Anomaly Detection: UR E26 calls for network monitoring and intrusion detection capabilities to be built into the vessel’s design or provided via the ship’s systems. The USCG rule explicitly expects continuous monitoring and real-time threat detection as part of the cybersecurity program. So both push operators toward deploying tools like IDS/IPS (Intrusion Detection/Prevention Systems) or managed Security Operations Center (SOC) services. If a ship or facility has implemented centralized monitoring per E26, it likely can feed that data into the compliance reporting needed for USCG (and vice versa).
• Incident Response and Recovery Plans: There is strong alignment in the requirement to have a documented Incident Response Plan and Recovery Plan. E26 obliges new vessels to carry an incident response plan for onboard cyber incidents and a recovery plan for getting systems back to operation. The USCG rule makes having a Cyber Incident Response Plan (as part of the broader cybersecurity plan) mandatory. Both would cover similar ground — isolation procedures, fail-over to manual operations (something E26 stresses and USCG would expect as well for safety), communication protocols, and steps to restore systems from backups. A vessel that already developed these plans for class compliance can integrate them into the USCG-mandated plan with relatively minor adjustments (mostly formatting and ensuring inclusion of reporting requirements and shore-side coordination).
• Backup and Restore Capability: UR E26 lists backup and restore as essential for recovery, and the USCG rule also requires robust backup strategies to support recovery. An E26-compliant vessel likely has, for example, an offline backup of its ECDIS charts and configs, and maybe an image of critical PLC programs; these measures directly satisfy the USCG’s requirement to be able to recover operations after an incident like ransomware or system failure. Both recognize that without backups, recovery is impossible.
• Supply Chain and Supplier Security: Indirectly, both frameworks push cybersecurity down the supply chain. UR E27 places requirements on equipment suppliers and integrators to deliver secure systems. The USCG rule expects operators to manage third-party risks and ensure contractors or service providers don’t become an attack vector. So if a ship was built under E27, its equipment suppliers have already been held to a security standard (e.g., perhaps requiring code signing on software updates or secure communication protocols) — this reduces the risk that a vendor’s poor practice undermines the operator’s security, aligning with USCG’s goal of mitigating supply chain risks.

In summary, an owner who has a new vessel classed to IACS E26/E27 will find that many USCG requirements are inherently met or easier to meet. The vessel’s technical infrastructure (zones, hardened systems, logging, etc.) is already in place to support things like monitoring, access control, and incident response. The class documentation for E26 (asset inventory, risk assessment, test results) can provide evidence for the USCG cybersecurity assessment and plan content. Both regimes speak the same language of cyber risk management, which is a big step toward interoperability.

Differences and Gaps Between the Frameworks

Despite alignment, there are important differences in focus and scope. Knowing these gaps is crucial for stakeholders to avoid blind spots. Some key differences are:

• Newbuild Design vs. Existing Operations: Perhaps the biggest difference is that IACS UR E26/E27 apply only to newbuilds (and are design/construction-focused), whereas the USCG rule applies to both new and existing vessels/facilities in operation, focusing on operational preparedness. A ship built in 2018 has no IACS cyber requirements retroactively applied (unless the owner voluntarily retrofits and pursues a class notation), but that same ship is subject to the USCG rule if it trades in U.S. waters. This means the USCG rule forces cybersecurity improvements on legacy systems and vessels, which E26/E27 did not cover. There could be a gap where older vessels need significant upgrades (segmentation, new software) to meet USCG mandates that a brand-new E26 ship would already have. For example, network segmentation: E26 requires it in design, but an older ship might have flat networks. The USCG rule effectively requires that older ship’s owner to now implement segmentation anyway (possibly by installing new firewalls or network devices) to comply. This is a gap in timing and scope — E26 is proactive at build, USCG is reactive across the fleet.
• OT vs. IT scope: IACS requirements are heavily OT-centric, emphasizing safety-critical control systems and minimizing focus on traditional IT like business networks, except where they connect to OT. The USCG rule, however, addresses both IT and OT systems that could impact maritime operations or security. It requires training for anyone with IT or OT access and considers data breaches (IT security) as part of reportable incidents. Therefore, an operator solely following E26/E27 might underappreciate the need to secure corporate IT systems or shore-side networks, which the USCG will expect in the cybersecurity plan. For instance, E26 might not explicitly require encryption of personal data or securing an office IT network, but if that IT network connects to a port terminal, the USCG plan must cover it. This is a gap — E26/E27 do not fully cover IT systems and human factors, whereas the USCG rule does. Bridging this requires extending the cybersecurity program beyond the engine room and bridge and into the company’s IT department and user behaviors (phishing training, etc.)
• Human Element — Training and Drills: IACS URs do not impose crew training or drills obligations; those are outside class scope (usually falling under ISM Code or company policies). The USCG rule squarely mandates cybersecurity training for personnel and regular drills/exercises. This is a gap if one were only adhering to E26/E27 — a vessel could be technically hardened but if the crew isn’t trained to recognize a phishing email or respond to a cyber alarm, the security posture is weakened. Shipping companies implementing E26/E27 will need to add a human element to satisfy USCG requirements. The cultural change and awareness that USCG pushes (making cybersecurity part of daily safety culture) is not covered by class rules except tangentially (class might ask if an incident response plan is in place, but not test crew knowledge). In practice, this means even an E26-compliant ship will need to implement a training program and conduct cyber drills (for example, a drill where the ECDIS is assumed to have failed due to cyber attack and crew must shift to paper charts and report the incident). This is why industry voices urge a holistic approach: compliance with technical standards alone (UR E26/E27) is not enough without investing in people and processes.
• Cybersecurity Officer vs. Roles in E26: E26 defines stakeholders (owner, integrator, supplier, class) with duties, but it does not require the shipowner to appoint a singular “cybersecurity officer” for the vessel. The USCG rule does — the CySO role. So, a company that built ships to E26 may have distributed cyber responsibilities (perhaps the IT department handles some, the superintendent others), but to comply with USCG they must formally assign a CySO and possibly reshape internal roles. This is a governance gap: the regulatory requirement for a named accountable officer is unique to the USCG rule. However, one could argue E26’s intent is that someone at the owner takes responsibility in each phase, which likely means in practice owners were already assigning someone to handle cyber during design/commissioning. Still, companies will need to translate that into an official role per USCG definitions.
• Plan Approval Process: Under IACS, the “cyber resilience” documentation (inventory, risk assessment, etc.) is reviewed by class as part of giving the ship its class certificate. Under USCG, the Cybersecurity Plan is reviewed by the Coast Guard for regulatory compliance. One question is whether these could be streamlined — e.g., will USCG accept an IACS cyber notation or class-approved cyber plan as evidence of meeting certain requirements? The ABS has asked if USCG would accept plans reviewed by Recognized Organizations on its behalf. As of now, that interoperability is not formally in place. So, there’s a potential duplication where an owner of a U.S.-flag newbuild might have to undergo both class plan approval and a separate USCG plan approval. Alignment in content helps (they likely contain similar info), but it’s still two processes. This is more a regulatory overlap than a technical gap, and efforts may be made in future to harmonize (for example, the Coast Guard could reference IACS UR compliance as a means of compliance for technical sections of the rule — but currently, the rule doesn’t explicitly do that).
• Legacy System Mitigations: E26/E27 don’t directly grapple with legacy system issues since they target newbuilds. The USCG rule has to address older, perhaps insecure systems currently in operation. This means the USCG may allow some risk-based concessions or compensating measures for legacy gear that cannot be fully secured (similar to how E27 allows compensating controls for systems that can’t meet a requirement). The challenge for operators is that a vessel built without cyber in mind might need substantial retrofits (e.g., installing an intrusion detection sensor on a 10-year-old ship network). E26/E27 adoption going forward will gradually reduce this legacy gap, but in the interim, companies will have to invest in upgrading existing fleet systems to meet the spirit of E26 even if not required by class.

Another difference is emphasis on documentation and evidence. Class requires evidence for compliance at build (test reports, supplier certification, etc.), while USCG will expect evidence of ongoing compliance (logs, drill records, audit results). A company used to satisfying class may need to bolster how it documents ongoing cyber maintenance for Coast Guard audits.

Synergies: How E26/E27 Adoption Mitigates USCG Compliance Risk

Given the above alignment, adopting IACS UR E26/E27 standards enterprise-wide can significantly mitigate the risk of non-compliance with the USCG rule — and improve cybersecurity overall. Some concrete examples of synergies include:

• “Baked-in” Security vs. Retrofit: If you have a fleet of newbuilds that were constructed to E26/E27, those ships arrive with robust cyber safeguards already in place. When it comes time to develop and submit a USCG Cybersecurity Plan for those vessels, the technical sections essentially write themselves. For instance, an owner can state that “the vessel’s networks are segmented into X zones (bridge, engine control, cargo control, etc.) with firewall rules as per class-approved design” — this directly addresses the USCG’s expectation for segmentation. In contrast, an older vessel without that segmentation might have to undergo an expensive refit or accept operational restrictions to manage the risk. Thus, E26 compliance de-risks the technical compliance with USCG regulations; there’s less scrambling to implement new controls by 2027.
• Incident Response Readiness: E26-compliant ships come with an Incident Response Plan and often some form of crew guidance for cyber incidents. While crew training may not have been rigorously done (unless the owner chose to), the existence of a plan and design features like manual fallback controls means the vessel is inherently more prepared to respond to a cyber event. The USCG rule’s drill requirements will be easier to satisfy on such a ship — you can run a meaningful drill because the systems support it. For example, an E26 ship has considered what happens if the main network goes down — perhaps there are independent gauges or an analog backup for a key reading. The crew can be trained to use those in a drill. An older ship might not have any backup if a digital system fails, making a cyber incident potentially crippling. Therefore, E26 features mitigate operational risk, which in turn means less risk of a serious incident that would put the operator in regulatory hot water.
• Documentation and Audit Trail: The process of complying with E26/E27 generates a lot of documentation — asset lists, risk assessments, test results, even Statements of Fact for exemptions. These can feed directly into the USCG Cybersecurity Plan as annexes or supporting materials showing due diligence. If a Coast Guard inspector asks, “How do you know what your critical systems are and that they’re secure?”, an E26 vessel operator can produce the class-approved risk assessment or the supplier type approval certificates showing compliance with E27 controls. This not only satisfies the question but demonstrates a level of rigor that likely exceeds what the USCG minimally requires, thus giving regulators confidence. In other words, class approval to E26/E27 can serve as a “seal of quality” or benchmark that the Coast Guard recognizes (even if informally) as a high standard.
• Reduced Vulnerabilities and Fewer Incidents: Perhaps the most important synergy is that a vessel or facility built/operated to the IACS standards will simply be more secure, and thus less likely to suffer a major cyber incident. Compliance risk is not just about paperwork; it’s also the risk of having a reportable incident or a security failure that could lead to penalties. For example, E27-compliant systems are far more likely to have up-to-date security patches and no default passwords, reducing the chance of an easy compromise. E26’s emphasis on detect and respond means an attack might be caught early, avoiding a full-blown Transportation Security Incident (which would bring intense scrutiny). Therefore, by adopting E26/E27 measures, companies indirectly protect themselves from the scenario of being the subject of a high-profile cyber incident that could result in enforcement actions, lawsuits, or reputational damage. It’s a form of risk mitigation that aligns with both safety and regulatory interests.
• Alignment with International Expectations: Many flag states and port states globally are looking at cybersecurity (IMO Resolution MSC.428(98) already requires cyber risk to be reflected in ISM safety management). A company that aligns its practices with IACS UR E26/E27 is effectively meeting a global benchmark. So if the operator moves ships between different jurisdictions, or if other nations introduce rules similar to USCG’s, the groundwork is already laid. This future-proofs the fleet. In the USCG context, if a foreign vessel comes into the US and has a class notation for cyber (indicating E26/E27 compliance), Coast Guard Port State Control officers conducting an inspection per their Work Instruction CVC-WI-027 will likely find a well-organized cyber risk management setup. That vessel is far less likely to be detained or face questions, because it meets or exceeds what the USCG is looking for via an internationally recognized standard. It helps avoid compliance friction at port state controls.

Illustrative Example: Consider a tanker company operating internationally with some vessels built in 2025 to IACS UR E26/E27 and some older vessels from 2010. In 2025, the company needs to comply with the USCG rule for any calling U.S. ports. The new E26-compliant tankers have detailed network diagrams, state-of-the-art firewalls separating cargo control from navigation systems, an onboard cybersecurity incident playbook, and equipment that is type-approved to withstand basic cyber attacks. The older tankers have more ad-hoc networks and rely on the crew’s best practices. When preparing the Cybersecurity Plans for these ships, the plans for the newbuilds sail through Coast Guard review — they show a high level of protection (MFA on control system logins, etc.) and the crew just needs the required training which is arranged quickly. During a spot inspection, one of the newbuild tankers experiences a minor malware incident on a bridge computer; the crew follows the incident response plan, contains it, and reports to the NRC as required — no significant disruption occurs. The Coast Guard praises the company’s handling. By contrast, one of the older tankers suffers a similar incident but due to a flat network, it spreads to the cargo load calculator, forcing a halt in operations. The crew was less prepared, reporting was delayed, and Coast Guard investigators get involved. The older ship faces a possible penalty for not adequately segregating networks (a requirement under the new rule). This example shows how E26/E27 adoption not only eases compliance but can prevent incidents that test compliance under fire.

Another example is on the facility side: A port terminal operator implements E26-like controls on its new automated cranes and gate systems (separating them from the corporate Wi-Fi, for instance). When writing its Facility Cybersecurity Plan, it maps those controls directly to the USCG requirements for protecting critical systems. It also points out that its crane control software was provided by a vendor who followed E27 guidelines, meaning it has authentication and logging. This significantly covers the USCG’s concern for securing operational technology. The remaining gap might be to ensure the terminal’s office IT network has similar protections — which the company addresses by extending policies enterprise-wide (inspired by E26’s holistic approach that you need global policies to support one vessel) The outcome is a robust plan that satisfies auditors and provides real security.

Towards Unified Maritime Cyber Resilience Standards

The interplay between IACS’s new rules and the USCG’s regulation is a case study in multi-layered governance: class rules ensure baseline technical integrity of vessels, while flag/port state regulations ensure operational governance and accountability. In the ideal scenario, these two are complementary. Indeed, we see strong complementarity — IACS UR E26/E27 set the stage so that complying with the USCG rule is far less onerous, and conversely, the USCG rule covers areas (like crew training and incident reporting) that class rules don’t, resulting in a more comprehensive overall cybersecurity posture.

There remain residual gaps that the industry and regulators will need to continue addressing. One is ensuring that older vessels are not left behind — class societies are encouraging application of E26/E27 practices to existing ships as far as practical (many offer voluntary notations for cyber for existing ships). The USCG rule effectively forces some retroactive upgrades, which is challenging but ultimately raises the floor for everyone. Another gap is international consistency: while the USCG rule is pioneering mandatory cyber regs, other jurisdictions might implement different approaches. IACS UR E26/E27 could serve as a harmonizing foundation globally (much like how IMO conventions rely on class for technical enforcement), suggesting that if more port states recognize or require IACS-level compliance, ships won’t face conflicting demands. The Coast Guard has signaled commitment to harmonization where possible (they intentionally aligned definitions with international standards, even though some misalignment with CISA’s regime occurred)

In conclusion, maritime cyber resilience is being strengthened on multiple fronts. For maritime cybersecurity officers, policy architects, naval engineers, and auditors, the message is clear: investing in IACS UR E26/E27 compliance is not just about class rules — it’s a smart strategy to meet regulatory requirements such as the USCG’s with confidence. It creates a virtuous cycle: better-built ships with cyber defenses suffer fewer incidents and easily satisfy regulators, which in turn reduces business risk and potential penalties. Conversely, the regulatory push (like the USCG’s) incentivizes operators to adopt the best practices encapsulated in E26/E27 even for vessels where it’s not mandatory — because doing so will likely become the expectation of safety inspectors and charterers worldwide.

Ultimately, bridging these standards leads to a more unified approach to maritime cyber resilience. A ship that is “born cyber secure” (E26/E27) and managed under a robust cyber risk program (USCG rule) is far better positioned to face the evolving threat landscape. By understanding the alignments and gaps, stakeholders can ensure no aspect of cybersecurity is overlooked. The result will be safer, more secure shipping operations that protect not only individual companies but the global supply chain and marine environment from cyber disruptions. The voyage toward maritime cyber resilience is ongoing, but with industry and authorities working in tandem, the course is set toward a safer digital horizon for the maritime domain.