The US and Israel launched a major joint military exercise yesterday as a deadline neared for Iran to approve a deal to delay its development of nuclear weapons and prevent Israel from attacking its nuclear facilities.

More than 1,000 US troops and 17 US Navy ships joined Israeli forces for a week-long missile defence exercise as it emerged that until recent progress in nuclear talks Israel may have been much closer to ordering a military strike than had been thought.

The deal to export much of Iran’s uranium to Russia and process it for civilian use should push back Iran’s acquisition of its first nuclear bomb by at least a year, analysts believe.

Iran has until today to approve the plan, which was provisionally agreed earlier this month. Until that point Israel was “on a glide path” to ordering a pre-emptive strike on Iranian nuclear facilities, one expert has said, echoing the privately-held views of some in the Obama Administration.

“The Israelis have been at pains to keep European governments and the US informed of their position, which is that if efforts to stop Iran’s enrichment are not going anywhere then this is going to force a difficult decision on the Israelis,” Patrick Clawson, of the pro-Israel Washington Institute for Near East Policy, told The Times.

Because of the uranium export deal being negotiated in Vienna “the US and Israel will not strike Iran’s nuclear facilities in the near future”, retired Brigadier General Shlomo Brom, of Israel’s Institute for National Security Studies, told The Jerusalem Post. “But the military option is not off the table.”

The Juniper-Cobra missile defence drill launched yesterday is an exercise held every two years but it serves as a timely reminder to an Iranian regime weakened by opposition demonstrations of the depth of Israel’s military alliance with the US.

Part of the purpose was to confirm that it could protect itself against attack from its regional enemies, one Cabinet minister said, adding: “We run these drills under a number of circumstances but it is clear that the scenarios are all based on a confrontation between Israel and Iran.”

Rear Admiral John Richardson, of the US Navy, said: “We hope this will contribute to the stability and security of this country. We hope for the best but are preparing for any contingency.” Iran was expected to give an answer today to a draft deal presented by the UN’s nuclear watchdog to ship 1.2 tons of enriched uranium — three quarters of its total stock — to Russia. It would then receive back lowenriched uranium, which can be used at small nuclear facilities but is not weapons-grade.

Israel has expressed hesitant support of the plan but has raised concerns that Iran would use it to buy time and still continue pursuing its nuclear weapons programme.

A team of inspectors is set to arrive at Qom on Sunday to take a first look at a newly-revealed enrichment plan there. Israeli officials said that Iran has regularly deceived inspectors on the intentions of its nuclear programme, using a complex system to hide military plants and complexes used to develop nuclear weapons.

Israeli defence officials were said to be concerned by their new estimates that show hundreds of targets within Israel that could be targeted by Iran. Israel’s plans for a strike on Iranian nuclear targets focus on just three facilities in Natanz, Isfahan and Arak.

Israeli officers said that the US would be testing a radar system installed in Israel a year ago to give early warning in the event of a missile launch.

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