Israel does not have much time to make a "fateful decision" about whether to strike Iran's nuclear sites, former U.N. Ambassador John Bolton said Sunday in a radio interview.

"Israel, I think, now faces the fateful decision whether it will allow Iran to get nuclear weapons, thus constituting a true existential threat to Israel," he said.

"Or whether they will strike as the Israelis have done twice before against nuclear programs in the hands of hostile states," Bolton told WABC Radio's Aaron Klein.

(Click on the screen below to listen to Bolton's comments:)

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"I don't think Israel has much time," Bolton continued. "Frankly, they should have done this years ago because we all know intelligence is imperfect and Iran may have a more developed capacity than we know about, perhaps in cooperation with North Korea."

Bolton spoke amid U.S. outreach to Iran and amid reports Iran's Revolutionary Guard announced Saturday they are committed to the slogan, "Death to America."

The former U.N. ambassador reacted to a statement by former Defense Secretary Leon Panetta, who said Thursday the while U.S. has "implemented unprecedented sanctions and pressure on Iran, we may very well have to use military force to back up our policy."

Bolton retorted: "If there is anybody left in Israel who thinks that the U.S. will use military force against Iran's program, they really need to seriously re-examine their basic values. It isn't going to happen under the Obama administration. I'll just say it again. It isn't going to happen."