Why the truce collapsed: The 'Article 5 Hormuz clause' tearing apart the US-Iran deal

"There was a truce — so why are they clashing again?"

The renewed military tensions between the United States and Iran trace back to the Strait of Hormuz, the world's most critical chokepoint for oil shipments. The MOU on ending the war that the two countries signed last month succeeded in halting full-scale hostilities, but left unresolved the most sensitive issue of all: the legal status of the strait. Analysts say the truce itself is now in jeopardy because both sides are reading the same clause in diametrically opposite ways.

BBC identified the "Article 5 Hormuz clause" as the single biggest reason the US-Iran truce remains unstable. Article 5 of the agreement states: "The Islamic Republic of Iran shall take its best efforts to ensure the safe passage of merchant vessels."

The sentence appears straightforward, but Washington and Tehran have interpreted it in opposite ways.

Iran argues the clause in effect recognizes its authority to manage the Strait of Hormuz. Tehran's position is that vessels must follow routes it designates and that oversight of the strait falls within its sovereign jurisdiction.

The United States, by contrast, reads the clause as requiring Iran not to interfere with international maritime traffic and to guarantee the free passage of strategic goods — including crude oil, LNG and fertilizer raw materials.

An executive at an Arab oil company in the Middle East told the BBC the ambiguity was glaring. "That clause has gaps wide enough to drive a truck through," the executive said.

The Strait of Hormuz is the world's largest energy transit corridor, carrying roughly 20 percent of global seaborne oil. Most crude from Middle Eastern producers passes through it on the way to Asia and Europe. For that reason, Iran regards control of the strait as its single most powerful strategic asset in negotiations with the United States.

Mohammad Baqer Qalibaf, Iran's chief negotiator, recently posted a pointed message on social media: "Keep your promises, or face the consequences," in an apparent warning to Washington.

The Iranian parliament has also recently introduced legislation titled the "Strategic Action for the Security and Sustainable Development of the Strait of Hormuz and the Persian Gulf."

Ebrahim Azizi, chair of the National Security Committee, said control of the Strait of Hormuz was "a non-negotiable right" and "a useful asset when confronting adversaries."

Washington has shown no sign of backing down either. President Donald Trump recently considered imposing a 20 percent transit fee on cargo passing through the Strait of Hormuz before dropping the idea, but instead resumed a maritime blockade of Iranian ports and stepped up military pressure.

Iran's recent attacks on vessels near Omani waters, and the US response of resuming airstrikes and the maritime blockade, are being analyzed as a real-world manifestation of the two sides' conflicting interpretations of the Hormuz clause.

Iran's moves have also drawn pushback from neighboring Gulf states. The UAE has expressed concern that Iran's assertion of management authority over the strait — through transit fees or service charges — could set a dangerous precedent. Oman, which served as a mediator, is also reported to have objected to Iran's inclusion of provisions for establishing a maritime service framework with Oman in the agreement.

Experts say the possibility of renewed negotiations remains open, as neither side wants a prolonged full-scale war.

Simon Gass, a former British diplomat who participated in the 2015 Iran nuclear negotiations, said there was no perfect solution but suggested a compromise was possible. "A formula in which Iran gains recognition of some management role through a service framework, without directly imposing transit fees, could be a middle ground," he said.

Robert Malley of the International Crisis Group said both Washington and Tehran expected the other to blink first, but that neither was likely to get everything it wanted. "The truce could be restored in some form," he said.