US President George W. Bush has given Israel the go-ahead to draw up a full plan of attack to take out Iran's main nuclear facilities and to present it to him for final approval, according to a senior Pentagon official who spokes to London's Sunday Times.

The official said the president had given Israel an "amber light," explaining that "amber means get on with your preparations, stand by for immediate attack and tell us when you're ready."

Israeli officials who had previously admitted to preparing for a possible strike on Iran's nuclear facilities said that such an attack would be impossible without a green light from Washington, as Israeli planes would need to travel through US-controlled Iraqi airspace. Israel would also need America's assistance in dealing with the diplomatic aftermath.

The Pentagon source said that the Bush Administration had already determined not to attack Iran, but noted that "the president is really preoccupied with the nuclear threat against Israel and I know he doesn't believe that anything but force will deter Iran."

Israeli Defense Minister Ehud Barak is scheduled to travel to the US on Monday where he will meet with various Pentagon officials to discuss how best to handle the Iran threat.

An aide to Iran's Supreme Leader Ayatollah Ali Khamenei warned on Saturday that if an attack is launched on his country's nuclear facilities, Iran will "destroy" Israel and 32 American military bases across the Middle East.

"If Israel and the US fire a bullet or a missile at Iran, its forces will attack the heart of Israel and 32 American bases in the region before the dust from such an attack has settled," Mojtaba Zolnour, Khameini's deputy representative in the Revolutionary Guards, told Iran's Fars news agency.

Iran last week held what it called a major test of its improved medium-range missile arsenal, indicating that it possessed the means to launch a substantial counter-strike against Israel.

However, Israeli and Western analysts who examined the missile test photographs so proudly distributed by Iran noted that they had been doctored. The Israelis further noted that the missiles in the photos appeared to be Iran's older Shihab-3 missiles, which are not capable of hitting Israel. The affair called into question Iran's ability to actually retaliate against Israel in the event of an aerial assault on its nuclear facilities.