The chief of Israel's Military Intelligence warned Thursday that some 200,000 missiles and rockets are aimed at the Jewish state at any given moment.

That's probably an exaggeration. But it reflects the daily barrage of warnings by Israeli leaders about the grave perils they say the country faces as tension mounts in the West's confrontation with Iran in the Persian Gulf over its contentious nuclear program.

This constant national focus on the threat of Iranian ballistic missiles, possibly nuclear-tipped, plus the missile arsenals of Hezbollah in Lebanon and Palestinian militants in the Gaza Strip, not to mention Iranian ally Syria, underlines the fear of many Israelis, and Western governments, that the right-wing coalition of Prime Minister Binyamin Netanyahu will unleash pre-emptive strikes against the Islamic Republic.

Many serving and retired military and intelligence leaders in Israel had warned that unilateral Israeli military action could trigger a catastrophic Middle East war that will drag in the Americans.

They're currently building their naval forces in the gulf as Iran's Revolutionary Guards stage massive exercises around the Strait of Hormuz, through which one-fifth of the world's oil supply passes.

The militancy of Israeli leaders troubles the administration of U.S. President Barack Obama, which has repeatedly cautioned Netanyahu not to act unilaterally.

But the growing concern in Netanyahu's government and Israel's increasingly powerful right wing is becoming stridently focused on the need to strike first to prevent a sustained and potentially cataclysmic missile bombardment of the Jewish state, the technological equivalent of the Nazi Holocaust.

Netanyahu and his allies want the Americans to move against Iran as well.

That's largely because they want the diplomatic cover but they know that Israel doesn't have the firepower on its own to deliver a knockout blow to Iran's nuclear program.

Concerns that Israel might decide to go it alone were fueled this week when hard-line Strategic Affairs Minister Moshe Yaalon, a former military chief of staff, declared that all Iran's nuclear facilities are vulnerable to airstrikes.

That defied the widely held conclusion Israel doesn't have the military capability to conduct the sustained offensive against Iran that would be required.

U.S. historian Gareth Porter, an anti-war activist, reports that U.S. Army Gen. Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff, told Israeli leaders Jan. 20 while visiting Israel that the United States wouldn't take part in a war against Iran begun by Israel without prior agreement from Washington.

"Dempsey's warning, conveyed to Netanyahu and Defense Minister Ehud Barak, represents the strongest move yet by … Obama to deter an Israeli attack and ensure that the United States is not caught up in a regional conflagration with Iran," Porter observed.

"But the Israeli government remains defiant about maintaining its freedom of action to make war on Iran, and it is counting on the influence of right-wing extremist views in U.S. politics to bring pressure to bear on Obama to fall in line with a possible Israeli attack during the election campaign this fall."

Porter noted that the "message carried by Dempsey was the first explicit statement to the Netanyahu government that the United States would not defend Israel if it attacked Iran unilaterally."

Netanyahu insists he'll never surrender Israel's right to act in its own defense "for anyone, including our American friends."

The abrupt postponement of a major joint U.S.-Israel exercise on missile defense scheduled for April added to the perception of deep differences on the security issue.

Neither side has offered a convincing explanation for the postponement but one conclusion has been that Israel wanted to maintain absolute military readiness for any contingency.

Israeli intelligence claims Iranian-backed Hezbollah's forces in Lebanon have more than 42,000 missiles and rockets. These include long-range weapons supplied by Iran and Syria that can hit anywhere in Israel.

These, along with hundreds of ballistic missiles held by Iran and Syria and shorter-range weapons in the hands of Gaza-based Palestinians, are deemed to constitute an almost existential threat to Israel.

The Israelis have said repeatedly the country's cities and towns could come under intense bombardment, with Hezbollah alone firing up to 400 a day for up to two months.

This would be an unprecedented attack on Israel's civilian population, far exceeding Hezbollah's 43-day bombardment of Israel's northern Galilee in the 2006 war.