Middle East flashpoint

How significant is the Strait of Hormuz?

The waterway, just 34km wide at its narrowest, is the world’s most important oil artery. Around 20 per cent of all the world’s oil flows through it. Iran has occasionally threatened to block the strait, a move that would be likely to trigger military action from the US and its allies.

Where else is Iran active in the region?

Iran has a wide network of allies and proxies in the Middle East which it supports with arms, financing, and military assistance. It backs Shia militia groups in Iraq and the Hizbollah militants in Lebanon as well as the Assad regime in Syria. It also provides some support to the Houthi rebels in Yemen and the Palestinian armed groups in Gaza.

What has caused the rise in tensions?

The US says it has intelligence indicating that Iran is preparing for attacks on American interests in the Middle East. One threat is ballistic missile attacks against US or allied ships in the region, according to officials in Washington, while another is some sort of action by Iranian-backed Shia militias in Iraq.

What is the US doing?

The Americans at first ordered an aircraft carrier strike group and a unit of B-52 bombers to reinforce US troops in the Middle East. Washington then announced that it was sending a Patriot battery designed to intercept missiles and an assault ship carrying US marines.

Will this lead to war?

Iran has so far responded only with rhetoric. It denounced the US deployments as “psychological warfare” and insisted that it was not intimidated. A senior Iranian official described the US aircraft carrier as a target, not a threat, but added: “If [the Americans] make a move, we will hit them in the head.”