Israel’s major allies in the West are working hard to talk it out of a unilateral military strike on Iran’s nuclear facilities, arguing forcefully that an attack ultimately would strengthen, not weaken, the rulers in Tehran.

The United States is leading the persuasion initiative, even though Washington largely has concluded that outside argument will have little effect on Israeli decision-making.

Iran’s regime says it wants to extinguish the Jewish state, and the West accuses it of assembling the materiel and know-how to build a nuclear bomb.

Israel fears that Iran is fast approaching a point at which a limited military strike no longer would be enough to head off an Iranian bomb.

Israeli Defense Minister Ehud Barak said on Thursday that the world increasingly is ready to consider a military strike against Iran if economic sanctions do not persuade Tehran to give up suspect parts of its nuclear program. Iran says its program is for peaceful purposes.

”Today as opposed to in the past there is wide world understanding that in the event that sanctions won’t reach the intended result of stopping the military nuclear program, there will be need to consider action,” Barak said in Israel.

Israeli officials asserted at a security conference on Thursday that Iran already has produced enough enriched uranium eventually to build four rudimentary nuclear bombs and was even developing missiles capable of reaching the United States.

Much of the agenda appeared aimed at strengthening Israel’s case for a strike, if it chose to make one.

President Barack Obama maintains that the U.S. is reserving the right to attack Iran if it one day feels it must, but an Israeli strike on Iran is more likely than a US one in the near term.

”Israel has indicated they are considering this, and we have indicated our concerns,” Defense Secretary Leon Panetta said on Thursday in Brussels.

Panetta would not comment on a published report that he fears Israel already has decided to go ahead.

A Washington Post opinion column by David Ignatius asserted on Thursday that Panetta believes there is a ”strong likelihood” that Israel will attack in April, May or June.

The US and its allies hope to hold off an Israeli strike at least until the latest round of sanctions, the first to hit Iran’s lifeblood oil sector directly, take effect later this year. They argue that a strike would do more harm than good and would endanger Israel and every nation perceived to be allied with it.

Western officials offered several of the arguments being laid out to Israel by the US, Britain, France and others.

The officials spoke on condition of anonymity to outline the sensitive diplomacy.

A senior Obama administration official said the US and Israel have similar views of the risk of an Iranian bomb and the timeframe in which the world could act. The US, however, sees a clear ”breakout” to nuclear capability by Iran as necessary before military action could be justified, the official said.

The official said the US is making its case publicly and privately but that the ultimate decision will be Israel’s.

The West is appealing to Israel’s self-interest, arguing that a military strike on known Iranian nuclear sites would not completely destroy Iran’s nuclear capability.

The US and others say it would not be effective except in the very short term, and ultimately would strengthen the Iranian regime by rallying Iranian national pride under attack and drawing sympathetic support from other Israeli enemies.

Some of the arguments are well-known, including that widespread and unpredictable Iranian retaliation would seed more violence in the Mideast and make Israel less secure.

That has been a US conclusion for several years.

A newer argument holds that the Iranian regime is weakened by years of sanctions and the implosion of its nearest ally, Syria, so it makes little sense to do something that would build it back up.

Some nations also are warning Israel that it would lose international backing if it should act outside international law.

European nations, especially, are wary of unilateral Israeli action.

US officials are careful on that point, saying the US bond with Israel is unbreakable.

As a practical matter, the United States would be bound to defend Israel in a full war with Iran.

A senior European diplomat said there are signs that some in Israel are receptive to the Western push to buy time with more sanctions that could further weaken the Iranian government. The Israeli government remains divided about the wisdom of a strike, the diplomat said.

Reflecting rising international alarm at the prospect of a unilateral strike, UN Secretary-General Ban Ki-Moon warned Israel on Wednesday that the standoff over Tehran’s nuclear program must be resolved peacefully.

British Deputy Prime Minister Nick Clegg expressed concern on Thursday that Israel could carry out a pre-emptive strike.