Barack Obama poised to announce the 'red lines' that would trigger a US attack ... - Telegraph.co.uk

With persistent speculation that Mr Netanyahu could order an attack before the US elections in November, Mr Obama has faced a delicate balancing act in his attempts to offer his ally a credible alternative to a military strike.

While he wants to demonstrate the sincerity of his warning that he will never allow Iran to acquire a nuclear weapon, he also wants to ensure that Tehran has a peaceful way out if it chooses to take it.

Seeking to demonstrate the seriousness of the president's intent, the United States and 25 other states will lead the largest-ever minesweeping exercise in the Persian Gulf later this month.

Officials say the manoeuvres are in direct response to Iran's threats to seal the Strait of Hormuz, the world's most important waterway. At the same time Washington is to place a new X-Band radar in Qatar, complementing two other systems erected in Israel and Turkey, that will be able to detect missile launches from across Iran.

The United States is also understood to be considering reviving intelligence attempts to sabotage Iran's nuclear facilities.

But even taken together, these steps are considered less important to Israel than a public declaration by Mr Obama about what would bring about American military action.

Disagreements over where the red lines should be drawn are still thought to persist, however. Israel wants to ensure that Iran is stopped before it develops the capacity to build a nuclear weapon and is pressing the Americans to impose a deadline after which sanctions will be replaced with force.

Mr Obama is believed to want more leeway and even as he has sought to reassure Israel he has taken steps to restrain it as well.

Washington is reported to have greatly reduced the scale of US participation in a joint military exercise to be held in Israel next month, slashing the number of troops to be deployed by two-thirds.

More significantly, the number of missile interceptors that were to be sent to Israel for the manoeuvres has also been reduced.

Some in Israel had seen the exercises as a cover to help the country defend itself from retaliation by Iran and its proxies if Mr Netanyahu launched an attack on Tehran's nuclear facilities. The scaled-back participation by the US could be meant to reinforce American warnings against a unilateral Israeli military strike, a former Israeli government official said.

Meanwhile, Iran sought to demonstrate that it had honed its ability to withstand an attack on its nuclear facilities yesterday, claiming that it was on the path to installing a sophisticated domestically-produced air defence system.

Brig Gen Farzad Esmaili, commander of the Khatam al-Anbiya air defence base, said that the Bavar 373 would be an improvement on the S300 missiles Iran was thwarted from acquiring from Russia because of international sanctions.

"The new system has higher and more developed capabilities than the S300 for discovering, identifying and destroying the targets while tracking them," he told a conference in Tehran.