The sinking of two merchant ships by the Houthis in July 2025 has reopened the Red Sea as an active conflict zone and reignited concerns over the safety of international shipping lanes. In addition, European and U.S. threats to re-enforce sanctions on Iran over their nuclear program will raise the threat to commercial shipping in the Strait of Hormuz over the coming months.
Red Sea: A Houthi return to form?
A lull in attacks by the Iran-backed Houthis on international shipping had been the status quo since January, after a ceasefire agreement was reached between Israel and Hamas over the conflict in Gaza earlier in the year. Houthi missile/drone attacks on commercial shipping in solidarity with the Palestinian cause were halted in kind. However, since then, developments in the region’s geopolitical situation – including the breaking of the Gaza ceasefire, renewed Israeli campaigns against Hamas, and the short but intense war between Israel and Iran in June – have prompted the Houthis to reassess their stance, and the Yemen-based rebel group has once again resumed its attacks on international shipping. Despite the announcement of a surprise deal between the Houthis and the U.S. in May, the terms of which included an agreement not to attack ships in the Red Sea in exchange for an end to American bombing of Yemen, recent attacks demonstrate how shipping perceived by the Houthis as linked to Israel remains at risk, while also raising questions over the robustness of the ceasefire.
More shipping losses: Magic Seas & Eternity C
In July, the Houthis carried out two major attacks on commercial ships near their waterways – the first successful direct missile/drone attacks undertaken since December 2024. On 6 July, the Houthis carried out an attack against the Liberian-flagged bulk carrier Magic Seas with unmanned surface vehicles (USVs), missiles, and small boats. The vessel was then boarded before explosives were placed and detonated onboard, resulting in the ship’s eventual sinking. All 22 crew members were rescued by a passing merchant vessel. Just one day later, the Liberian flagged cargo ship Eternity C was subjected to a similar attack, involving USVs and small arms fire attacks from small boats, with the Houthis further targeting and sinking the vessel with unmanned aerial vehicles (UAVs) and antiship missiles. Later rescue missions managed to recover some of the Eternity C’s crew, with 10 rescued and taken to Saudi Arabia, a further 10 held by the Houthis, and five more believed deceased.
These attacks, involving USVs, UAVs, and missiles, represent a significant re-escalation in the severity of Houthi activity targeting commercial shipping in the Red Sea, and a seeming breach of the U.S.-Houthi ceasefire deal. However, the Houthis claim that both the Magic Seas and Eternity C were linked to trade with Israel, and the group maintains that its attacks on Israel-linked vessels are legitimate and also in accordance with the agreement not to attack neutral ships in the Red Sea and Gulf of Aden. On July 27, the Houthis publicly announced a “Fourth Phase” of their naval blockade in the Red Sea. As such, risks to commercial shipping in the region have risen once more, with further Houthi attacks likely.
Strait of Hormuz: Iranian jamming intensifies
Outside of the resumption of Houthi attacks on international shipping in the Red Sea, the Iranian regime has also carried out a series of actions impacting normal shipping operations near its territorial waters in the Persian Gulf. Iran has operated electronic warfare (EW) platforms for decades and frequently deploys such tools in the Strait of Hormuz. Although the primary function of this equipment is to protect infrastructure from surveillance and attacks – including by jamming Global Navigation Satellite Systems (GNSS) used by UAVs and guided munitions – Iranian EW activity, whether incidentally or otherwise, has an impact on shipping in the Strait of Hormuz.
The United Kingdom Maritime Trade Operations (UKMTO) reported several cases of ships’ identification systems (AIS) and global positioning systems (GPS) being disrupted in March. This interference accelerated amid hostilities between Israel and Iran in June, with reports suggesting 1,000 vessels were affected each day, and although Iran and Israel have ceased their kinetic military exchanges, interference patterns continued well into July. These incidents have been wide-ranging, with blanket interference reported across swathes of the Persian Gulf and the strategically important Strait of Hormuz.
Although the waterways near Iran remain open to shipping, risks facing vessels have increased due to Iranian jamming activity. Any complications for navigation or ship-to-ship communication – which helps prevent collisions and aids traffic management, especially vital for the Strait of Hormuz as a maritime chokepoint – could have disastrous consequences for ships opting to transit the region, in addition to hindering efforts to respond to vessels in distress.
The data: An uptick in antishipping activities
Public data relating to maritime attacks and other incidents affecting commercial shipping in the Indian Ocean is curated by UKMTO, which operates a monitoring scheme for the Voluntary Reporting Area (VRA), including coverage for the Red Sea, Gulf of Aden, Persian Gulf, the Strait of Hormuz, and the Arabian Sea.
Maritime incidents affecting commercial shipping in the VRA, as reported to UKMTO, have been trending downwards since the start of 2024, and 2025 has seen far fewer incidents when comparing each month’s data to the year prior. This was down to a decrease in missile/drone attacks carried out by the Houthis; in H1 2024, the Houthis carried out an average of 10 missile/drone attacks per month, but by H2 2024, this had fallen to just 3.5 per month. For 2025, the Houthis have carried out just two missile/ drone attacks on commercial shipping, namely the attacks on Magic Seas and Eternity C in July, with the other missile/drone incident recorded this year by UKMTO being an Israeli airstrike endangering maritime operations near the port facilities at Al Hudaydah in May.
What is also notable is the recent increase in irregular activity; in this case, “irregular activity” since March 2025 is exclusively related to electronic interference, including GNSS jamming and spoofing. In the Red Sea, there has been a significant increase in vessels reporting such interference, with the UKMTO highlighting that the southern portion of the Red Sea between Jeddah and the Bab-al-Mandeb strait has been most affected. Within this area, widespread GPS interference has also been noted in the waters near Port Sudan, which has, in many cases, lasted hours and forced vessels to rely on backup navigational methods. In the Strait of Hormuz, Iranian EW activity is having a major impact on both GPSbased navigation and vessels’ positional reporting through AIS.
Tehran under pressure
Recent political developments on the international stage may be serving to force the Iranian regime to underscore its status as a regional player. Recent discussions have circulated regarding the employment of the ’snapback mechanism’ provision of the 2015 Joint Comprehensive Plan of Action (JCPOA), more commonly known as the Iran Nuclear Deal. The JCPOA ‘snapback mechanism’ would allow the United Nations to reimpose a raft of economic and political sanctions for the first time in a decade against Iran for non-compliance with the agreement. France, Germany, and the U.K. have had preliminary meetings with Iran on a deal but have set a deadline of progress on the nuclear talks for 29 August, or they will utilize the mechanism. The measures must be invoked before they expire on 18 October, with French officials stating the JCPOA provisions will be triggered by the end of August at the latest.
Tehran has said that “tensions could escalate irreversibly” if the JCPOA mechanism is invoked. Given the late August timeline suggested by French officials and the 18 October expiry of the mechanism, it is possible that Iran will soon be compelled to demonstrate that it retains the capability to be a disruptor in the region. The ability to threaten globally significant maritime transit routes is an increasingly prominent component of Tehran’s forward deterrence doctrine, having seen its Hezbollah and Hamas proxies eroded and its missile forces arguably achieve little strategic effect during its recent war with Israel.
Indeed, Tehran has many options with which it can impact shipping, with varying levels of deniability, severity, and related potential for escalation that it could choose to deploy in order to influence talks or respond more decisively to hostile economic measures. These options can range from ‘grey zone’ activity to direct military action.
Iran’s options
Demonstrative disruptive activities
Iran could opt to carry out disruptive activities using its personnel through a demonstrative show of force. This would entail harassing ships and their crews in order to gain leverage during talks and demonstrate Iranian preeminence over the Persian Gulf. This option is the most likely and represents a continuation of the type of asymmetric tactics already utilized in the region, including using EW systems for jamming, harassing civilian crews with military ships, demanding to inspect vessels’ cargoes and manifests, confiscating supposed contraband, and seizing and impounding vessels.
Limited kinetic action
Outside of a full blockade of the Strait of Hormuz, Iran could seek a more restricted approach, carrying out limited actions to selectively target vessels rather than applying a blanket policy of disrupting all maritime traffic in and out of the Strait. This option would represent a less flagrant escalation of tensions, operating below red lines that would trigger an international military response, and would primarily affect vessels owned and operated by Iran’s perceived opponents (Israel, the U.S., etc.) with less disruption of commercial traffic of its allies and potential supporters (Russia, China, etc.).
Closing the Strait of Hormuz
As a last resort option, Tehran could entirely disrupt maritime traffic by closing the Strait of Hormuz to civilian ships. This is considered to be an extreme approach only if the regime is facing an existential threat. Closing the Strait would disrupt Western shipping but would also majorly impact Iran’s own economy (which relies heavily on petrochemical exports via the Strait) and would serve to further isolate Tehran in the Gulf.
Outlook: Stormier seas
The security environment for maritime operations in the Middle East is once again deteriorating, with renewed threats in both the Red Sea and the Strait of Hormuz. The resumption of Houthi attacks on civilian shipping underscores the risk of rapid escalation, accompanied now by a formal announcement of a renewed campaign against shipping by the Houthis, despite previous ceasefire agreements. With previous military and diplomatic responses so far offering limited long-term effectiveness, the elevated risk looks unlikely to abate in the near term.
At the same time, rising tensions between Iran and Western powers over nuclear developments and the JCPOA ‘snapback mechanism’ could trigger an increase in Iranian asymmetric activity in the Persian Gulf and Strait of Hormuz. As previously evidenced, Tehran may seek to counter international pressure and assert its regional influence by targeting maritime traffic and demonstrating its ability to disrupt global markets.
As a result, commercial vessels – particularly those with Western or Israeli affiliations – will continue to face heightened threats through the remainder of 2025.