FOR the third time in as many months, the crew of an oil tanker found themselves at the centre of an international incident. The British Heritage, a vessel owned by BP, a British oil firm, was sailing east through the Strait of Hormuz on July 10th when three Iranian gunboats allegedly tried to halt its passage. They soon backed down and allowed the tanker to continue—but only because it was trailed by the HMS Montrose, a British warship. Reports suggest that the frigate had trained its guns on the Iranian boats. The latter would have been manned not by Iran’s regular navy but by the Islamic Revolutionary Guard Corps (IRGC), which operates small attack craft in the Gulf.
The Guards deny there was any “confrontation” with a tanker, British or otherwise. Such denials ring increasingly hollow—not least because, days earlier, a guards commander threatened to seize a British vessel. His threat was a response to the capture on July 4th of the Grace 1, a Panama-flagged tanker laden with Iranian crude that was raided by British marines as it passed off the coast of Gibraltar.
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Britain says it seized the Grace 1 because its cargo was destined for Syria, which is under European sanctions. But to Iran the incident looked like another front in America’s campaign of economic warfare. Since May 2018, when Donald Trump withdrew from an agreement that swapped sanctions relief for limits on Iran’s nuclear programme, his administration has applied ever-harsher measures to choke Iran’s economy. Analysts estimate that its oil exports in June fell as low as 300,000 barrels a day (b/d), barely one-tenth of the 2.5m b/d it shipped before Mr Trump withdrew from the deal.
After a year of restraint, Iran has begun to strike back. Until now, though, it has done so in ways that offered a dubious measure of deniability. Four oil tankers were sabotaged in May near the United Arab Emirates’ port of Fujairah, and two others were damaged by explosions in the Gulf of Oman last month. Diplomats in the Middle East have little doubt that Iran or its allies were responsible, and America has blamed Iran, but investigators have not yet assigned blame for either incident. America and Iran came close to blows last month after it shot down an American surveillance drone near the Strait of Hormuz; Mr Trump rescinded his order for retaliatory strikes moments before they were due to take place, and was reported to have ordered a cyberattack instead.
The standoff with the British Heritage is the first time Iran has taken aim at one of the remaining state parties to the nuclear deal. Relations between Britain and Iran have long been bristly, and the two have on occasion been involved in naval confrontations. In 2007, for instance, IRGC naval forces surrounded and captured a boarding party of 15 British sailors off the coast of Iraq and Iran; they were released a fortnight later.
On the nuclear front, Iran has also started to ignore its own commitments under the 2015 agreement. First it broke a 300kg limit on the amount of low-enriched uranium it may stockpile. Then it started enriching the stuff to 5% purity, above the agreed-upon 3.67% limit. That is still far short of the 20% threshold that would put it on a quick path to weapons-grade uranium. But it is a second clear violation, and Iran has threatened further breaches every 60 days unless the other signatories help it cope with America’s unilateral sanctions.
On July 9th the foreign ministers of Britain, France and Germany called for a joint meeting of the deal’s remaining parties. They have not yet invoked the deal’s dispute-resolution panel, which they view as a last resort: the lumbering mechanism could end with the United Nations restoring multilateral sanctions on Iran. That would sink the deal for good. At some point, though, they will have no choice but to convene the body.
Critics of Mr Trump’s “maximum pressure” strategy lament, rightly, that the president does not know what he wants to achieve. Aides have variously called for regime change, a grand bargain that reshapes Iran’s foreign policy or a slightly tougher arms-control agreement. Mr Trump has, at times, seemed to embrace all three goals. Europe has the opposite problem. It has a clear objective—preserving the agreement—but no practical means to achieve it. Major European firms will not risk American sanctions to do business in Iran. Instex, a “special-purpose vehicle” meant to allow humanitarian trade, took a full year to set up and will not help much. Its starting capital of only a few million euros is laughably small.
As the threats to shipping mount, America wants to set up a coalition to escort vessels in both the Gulf and the Bab al-Mandab, a narrow passage off the coast of Yemen that leads to the Suez Canal. A Saudi military spokesman claimed on July 8th that the Houthis, a Yemeni militia with ties to Iran, tried to attack a commercial ship in the strait earlier this week (though the Saudis have provided no evidence). That seems sensible enough: Wednesday’s incident could have been much worse if the British Heritage had lacked a naval escort. But it is also a sign that America only expects this crisis to worsen.