JERUSALEM (Reuters) - Ballistic missiles could be Israel's weapon of choice against Iranian nuclear facilities if it decides on a pre-emptive attack and deems air strikes too risky, according to a report by a Washington think-tank. Israel is widely assumed to have Jericho missiles capable of hitting Iran with an accuracy of a few dozen meters (yards) from target. Such a capability would be free of warplanes' main drawbacks -- limits on fuel and ordnance, and perils to pilots.

Israel, whose jets bombed Iraq's nuclear reactor in 1981 and mounted a similar sortie over Syria in 2007, has hinted that it could forcibly deny Iran the means to make an atomic bomb.

Toukan, whose 114-page report frowns on the prospect of unilateral Israeli action, said a Jericho salvo could draw an Iranian counter-attack with Shehab missiles. Other reprisal scenarios include Iran choking off oil exports, hitting U.S. Gulf assets, or ordering proxy attacks on Jewish targets abroad.

Some Israeli experts have been dismissive of the Shehab threat, citing intelligence assessments that Iran has deployed fewer than 100 of the missiles and that, if launched, most would be destroyed in mid-flight by Israel's Arrow II interceptor.

"Under such circumstances, we would expect little more than a repeat of the Gulf war," said one ex-general, referring to Iraq's firing of 40 Scud missiles at Israel during the 1991 conflict. Those attacks inflicted damage but few casualties.