The Israeli military has begun computer-testing its anti-missile systems to determine how effective they would be against an all-out bombardment by thousands of rockets, everything from Iran's ballistic Shehab-3s to Hezbollah's Iranian Zelzals and Hamas' Grads.

The Israeli daily Haaretz reported that Operation Tiramisu, named after a multilayered Italian cake, is designed to test how well the systems, some not even in place yet, "would cope with a simultaneous barrage of missiles at every possible altitude and trajectory."

The operation took on a particular resonance because of the rift between Prime Minister Binyamin Netanyahu's right-wing government and the administration of U.S. President Barack Obama over Netanyahu's refusal to halt all settlement-building in the occupied West Bank.

The political rift, seen by some as the worst since President Dwight Eisenhower forced Israel -- along with the British and French -- to withdraw from Egypt in the 1956 Suez Canal war, has heightened concerns about Israeli pre-emptive strikes against Iran's nuclear facilities.

Should Israel take such unilateral action, in defiance of U.S. warnings not to, the Jewish state could face the kind of sustained missile barrage the military is simulating on its computers.

The tests reflect the gnawing realization in Israel that such an unprecedented attack from all sides, possibly sustained over several weeks, may overwhelm their still-unfinished multilayered defense shield against missiles of all types.

The only element of this shield currently in place is the Arrow-2 missile system designed to shoot down ballistic missiles at long range and high altitude. The $2 billion system, largely funded by the United States, is built by Israel Aerospace Industries, the state-owned flagship of Israel's defense industry.

A more advanced variant, known as Arrow-3, capable of downing hostile missiles outside the Earth's atmosphere, well away from Israeli soil, is being developed but Arrow has never been tested in combat.

The Iron Dome system built by Rafael Advanced Defense Systems is the lower tier of the defense shield. It only completed test-firings in January and the first battery is being deployed now, reportedly along Israel's northern border with Lebanon.

Iron Dome is designed to counter rockets with a range of 40 miles or so, the type of projectile that makes up much of the 45,000 rockets that Defense Minister Ehud Barak recently claimed Hezbollah possesses.

Its development was spurred by the 2006 war between Israel and Hezbollah, when the Iranian-backed organization unleashed some 4,000 rockets against Israel during the 34-day conflict. Only one was shot down, by an aircraft.

The third, intermediate layer will be occupied by a system known as David's Sling, which will tackle missiles with as range of several hundred miles. But it is still in development with Rafael and won't be ready for another couple of years, according to Israeli officials.

"One aim of the exercise was to see how each system would function as a backup for the others after a failure to shoot down an incoming missile at the first attempt," Haaretz reported.

"Results of the computer testing will give the Israeli air force a better idea of where best to deploy its anti-missile systems, as well as helping commanders draw up recommendations to the Defense Ministry over how many batteries of each type it should acquire."

The simulations will also help the military decide whether it should establish an operations center that won't only integrate all three Israeli systems but U.S. systems such as the Patriot PAC-3, Aegis and THAAD that were employed in a large-scale joint missile defense exercise in Israel, Juniper Cobra, last November.

Many of the missiles being ranged against Israel are more advanced than those used by Hezbollah in 2006. They are more accurate, have greater range and carry more destructive warheads. Their main targets will almost certainly be urban population centers.

According to some Israeli reports, not confirmed by independent sources, Syria has been training Hezbollah units on Soviet-era SA-2 and SA-3 surface-to-surface missiles.

Damascus has also supplied Hezbollah with the Syrian-built Fateh-110 missile, a solid-fuel, road-mobile weapon with a range of around 150 miles and capable of carrying a warhead containing a half-ton of explosives.