July saw mounting tensions between Britain and Iran, as first the British Navy seized an Iranian oil tanker off Gibraltar and then Iran’s Revolutionary Guard Corps did the same to a British vessel in the Strait of Hormuz. These moves added a new dimension to the uncertainty surrounding the ongoing diplomatic impasse between Iran, the leading European countries, and the United States. Affecting the delicate balance in the Strait of Hormuz, the standoff significantly increases the risk that miscalculations — or simple opportunism — could spill over into military confrontation.

This tension is rooted in Tehran’s recent response to a series of controversial maneuvers by Donald Trump’s administration, which culminated in threats of open warfare in the last few months. This started when Trump unilaterally withdrew from the Joint Comprehensive Plan of Action (JCPOA) on May 8, 2018, and then imposed a sanctions regime that also targeted Iran’s vital oil exports.

The JCPOA was a landmark agreement between Iran and the P5 +1 (the five permanent members of the UN Security Council — the United States, Russia, China, France and the United Kingdom — plus Germany) signed in 2015; it provided clear guarantees and restrictions on Iran’s civilian use of nuclear technology, in exchange for the lifting of economic sanctions. Exactly one year after Trump’s move, on May 8 this year Tehran announced that, if the EU bloc (the United Kingdom, France, Germany) continued failing to deliver the promised financial mechanism to bypass US secondary sanctions, Iran would gradually decrease its adherence to its JCPOA commitments.