But Iran has stirred in, too, some mollifying gestures and clearly hopes to play a clever game, one step back from the brink of outright provocation.

The question is whether it might provoke more than it has bargained for, at a point when Washington is inclined to see the Lebanon conflict as a proxy war between Iran and the US.

Iran said yesterday that it would launch a series of huge “war games”, or military practice manoeuvres. They were “aimed at introducing Iran’s new defensive doctrine”, said a military spokesman, General Mohammad Reza Ashtiani.

For all the liberal use of the word “defensive”, this is hardly a friendly stunt. The war games — dubbed “Blow of Zolfaghar”, in reference to a sword that belonged to Imam Ali, one of the most revered figures of Shia Islam — are designed to show that Tehran is standing up to the superpower. “Our army is ready to defuse all plots against the Islamic Republic of Iran”, Ashtiani added. Iran is all too aware of the US forces on its borders in Iraq and Afghanistan.

The Interior Ministry also said this week that Iran would boost patrols on its borders — while adding that this was merely to target drug smugglers.

These bristly gestures will only add to regional tension. Iran has denied accusations by the US and Israel that it has funded and armed Hezbollah, the Lebanese guerrilla force. It has helped it only through inspiration, it says.

But the US fears that Iran has used Hezbollah to extend its influence throughout a “Shia crescent”. Iran is a largely Shia Muslim country; it is the mentor of the Shia fighters of Hezbollah; while Iraq is now led by its Shia majority.

These tensions will come to a head on Tuesday, Iran’s selfimposed deadline for replying to a proposal from the US and European Union, who are trying to persuade it to back down on its nuclear work. They suspect that Iran’s development of civil nuclear power is a cover for military ambitions, something that Iran denies.

Under the offer, other countries, including the US, would help Iran to run a civil nuclear programme. They would supply it with fuel for its reactors, so that it had no need to master uranium enrichment, the most controversial work, which would also equip Iran with the skills to make a bomb.

This week Iranian officials appeared to offer an olive branch, saying that they were prepared to talk about suspending uranium enrichment.

European officials greeted this with exasperation, however, calling it a delaying tactic and saying that suspension of that work was a condition for any talks to begin.

In any case, President Ahmedinejad repeated his usual uncompromising stance yesterday. He said: “How can the Iranian nation give up its obvious right to peaceful nuclear technology when America and some other countries test new atomic bombs each year?” The United Nations Security Council has set a deadline of August 30 for Iran to stop enrichment or face sanctions. Yesterday a top US negotiator said that the US intended to move “very quickly in the first part of September” to impose sanctions if Iran had not stopped.

The penalties “will be well deserved” said Nicholas Burns, Undersecretary of State, who has carried out much US diplomacy on the Iranian threat. “It’s not a mystery to the Iranians what is going to happen.”

He added that the US’s Arab allies, led by Saudi Arabia, were also concerned about Iran’s ambitions in the region. “There is broadened concern about the policy of a country that flexes its muscles,” he said. “Iran wants to be the dominant country in the region.”

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