Strait of Hormuz 'faultline' exposes weakness of the US-Iran deal
Control of the waterway has become a key point of contention between the US and Iran, as a ceasefire deal falters.
The fragile "no war, no peace" situation since the US and Iran signed a tentative deal last month now seems to have tipped into war.
This on-again off-again truce could again wobble back into life through the efforts of increasingly exasperated Arab and Pakistani mediators, and the preference of both sides to avoid a return to a drawn out, all-out war.
But its biggest fault line is the status of the strategic Strait of Hormuz - and Iran is again making it clear that its control over this vital maritime corridor is a big, bright red line that neither military, economic nor diplomatic pressure can break.
"We told you: keep your word or pay the price," is how Iran's lead negotiator Mohammad Bagher Ghalibaf recently phrased it on social media, quoting the agreement.
Why the Strait of Hormuz matters so much in the Iran war
Tehran has found backing for that word in the very vague details of the deal - known as a memorandum of understanding - which was drafted in haste in June.
It has been understood differently by both sides from the start.
Iran sees in point five of the 14-point plan a green light, which gives it sway over the management of this critical maritime corridor. Point five reads: "The Islamic Republic of Iran will make arrangements using its best efforts for the safe passage of commercial vessels."
The US reads that as saying Tehran has to open this strategic strait to the free flow of global oil and gas supplies, along with other vital commodities, including ingredients to produce fertiliser.
"You can drive a truck through those clauses," an Arab oil executive working in the region said.
While the new leadership, which emerged in Tehran from weeks of all-out war and waves of US-Israeli assassinations, appears to be aligned on their broad strategic vision for this new chapter of the Islamic Republic, there are clear and growing signs of splits over how to move forward.
"Some want to cash in on battlefield gains through diplomacy and some believe the ceasefire came too soon before Iran had inflicted enough pain on the US," assesses Robert Malley of the International Crisis Group, who was part of the US delegation that negotiated the landmark 2015 nuclear deal US President Donald Trump pulled out of in his first term.
Recent Iranian attacks on three vessels including a Qatari-flagged liquefied natural gas tanker, moving through a shipping corridor close to Oman's coastline to the south, were described by a diplomatic source in the region as the work of a "rogue unit" within the Islamic Revolutionary Guard Corps (IRGC).
In a system where the IRGC now plays a dominant role, Iran's non-negotiable red line is that vessels must now stick to its designated routes.
Last night, far from the thunder of this escalation, its parliament quietly introduced a new bill to manage the strait called the Strategic Action for the Security and Sustainable Progress of the Strait of Hormuz and the Persian Gulf.
That news was posted on X by Ebrahim Azizi, head of the assembly's national security commission, who told us in April that controlling the waterway was Iran's "inalienable right".
When asked when Iran would cede control, his reply was short and sharp – "never."
He described it as an "asset to face the enemy".
Iran's zero trust in the US' promises, fuelled by the repeated eruptions of war or threats during negotiations, have cemented its resolve.
Control over the strait is seen not just as a bargaining chip in this impasse, it also sees it as its new leverage, a new form of deterrence, as well as an economic lifeline - in case sanctions never get lifted, and its assets worldwide remain frozen.
But Tehran's determination to rewrite the rules in the region is also causing tension with its neighbours including Qatar, one of the main mediators in this crisis, as well as Iran's longstanding traditional ally Oman, which has played a role for decades behind the scenes.
Countries like the United Arab Emirates have made it crystal clear that Iran's plans to play a controlling role, including charging some form of "service fees" is unacceptable and sets a dangerous precedent.
A source informed on the back and forth said Oman had objected to Iran's inclusion of a specific mention in the agreement in that same contested fifth point - that Iran "will conduct dialogue with the Sultanate of Oman to define the future administration and maritime services".
Muscat now finds itself caught between the wishes of Washington, and Tehran wants to maintain, above all else, its longstanding reputation as the region's discreet diplomatic middleman.
