US Secretary of State Marco Rubio began a three-day tour of the United Arab Emirates, Kuwait and Bahrain on Wednesday, his first high-level mission to the region since Washington and Tehran signed a memorandum of understanding (MoU) that halted four months of war. The visit, which includes a Gulf Cooperation Council (GCC) meeting in Manama, is aimed at reassuring allies who were targeted by Iranian missile and drone strikes during the conflict and who now question whether the preliminary accord adequately addresses their long-term security. According to US officials, Rubio told leaders in Abu Dhabi and Kuwait City that Washington would “not do anything that undermines the security of our allies” and would keep them “completely aligned” on all decisions related to the negotiations with Iran.

Gulf capitals have publicly welcomed the cessation of hostilities but, according to diplomats briefed on the talks, remain wary of the MoU’s gaps. The document sets a 60-day framework for a permanent settlement but does not cover Iran’s ballistic missile programme or its network of regional proxies — the very capabilities that struck the UAE, Kuwait and Bahrain during the war. A proposed $300 billion reconstruction fund for Iran, mentioned in the accord, is viewed in some Gulf assessments as a potential source of military recapitalisation. Rubio’s meetings with Emirati President Sheikh Mohamed bin Zayed Al Nahyan and Kuwait’s Emir Sheikh Meshal al-Ahmad al-Sabah focused on these concerns, with the US side emphasising that technical talks resuming at the end of June would address nuclear inspections, sanctions relief and other unresolved issues.

The most immediate point of friction is the status of the Strait of Hormuz. Iran and Oman, which border the waterway, have asserted sovereign rights to impose maritime service fees on transiting vessels, a position Tehran has repeated since the MoU was signed. Rubio countered that “no country is allowed to charge tolls or fees on an international waterway,” a stance he said was shared by all nations. US President Donald Trump wrote on social media that Iran had pledged “NO TOLLS, NO INSURANCE COSTS, & NO OTHER CHARGES OF ANY KIND,” but did not specify whether that commitment extends beyond the 60-day negotiating window. Qatar’s prime minister travelled to Oman to initiate parallel talks among Gulf states, Iraq and Iran on the strait, with Gulf countries expected to push for toll-free navigation while Iran seeks an environmental and security service fee, according to a diplomat cited by Agence France-Presse.

The Rubio tour comes as the technical track of US-Iran negotiations prepares to reconvene, likely in Switzerland around 29 or 30 June, with experts from the State Department, the Department of Energy and other agencies. The MoU also commits Iran to allow International Atomic Energy Agency inspectors access to its nuclear sites, though Iranian officials have given conflicting signals on the scope of inspections. Meanwhile, US-mediated talks between Israel and Lebanon continued in Washington, with Rubio stating that the presence of Israeli forces in southern Lebanon was a response to Hezbollah attacks and that Washington hoped the Lebanese armed forces would eventually assume full control of the territory. The GCC meeting in Bahrain on Thursday is expected to produce a joint statement on the negotiations, as Gulf states seek to translate US assurances into concrete guarantees ahead of the next round of technical discussions.