Incoming U.S. Secretary of Defense Robert Gates told a Senate committee on Thursday that Israel has nuclear weapons, and that this partially explains Iran's motiviation to acquire nuclear weapons.

"They are surrounded by powers with nuclear weapons - Pakistan to their east, the Russians to the north, the Israelis to the west and us in the Persian Gulf," he told the Senate committee during his confirmation hearing.

Though Israel is widely assumed to have a nuclear weapons arsenal, it has stuck to its policy of ambiguity on the subject, insisting against all the evidence that it will not be the first to introduce nuclear weapons into the Middle East. A retired Israeli general said Thursday Israel is no longer trying to convince anyone that it has no nuclear arsenal.

Israeli officials traditionally do not respond to statements like the one Gates made, and true to form, government spokeswoman Miri Eisin told The Associated Press, "there is no direct Israeli comment."

Experts played down the importance of Gates' "outing" of the Israeli nuclear weapons program. Defense analyst Shlomo Brom, a retired Israel Defense Forces general who was once in charge of strategic planning for the military, said similar statements came out of Washington during the first Gulf War in 1991 and did not lead to a change in Israeli policy. "This is nothing really new," he said. "It doesn't change anything."

What has changed over the years is the perception of Israel's nuclear capabilities. In 1986, Mordechai Vanunu, a former technician at Israel's main nuclear reactor, gave pictures and documents to the London Sunday Times that led experts to conclude that Israel has a sizable nuclear weapons arsenal, ranking it sixth in the world. Vanunu served an 18-year prison term for his disclosures.

The pictures and other evidence put Israel's official policy in a new light. "The fact is that for a long time, Israel's policy of ambiguity has been not a matter of people thinking we don't have any [nuclear weapons], just that Israel doesn't admit it," Brom said.

Even so, Israel has consistently maintained its policy of ambiguity. Analyst Yossi Alpher said it allows Israel's neighbors "to assume that even if Israel had nuclear weapons, this was not a threat to them," and therefore it should not be changed. However, Alpher added, "it's very possible that if and when Iran goes nuclear in the military sense, Israel will have to consider ending its policy of ambiguity. Then it won't be the first."

At a news conference in Tel Aviv on Thursday, Prime Minister Ehud Olmert responded to Gates' explanation of Iranian motives for acquiring nuclear weapons.

"I don't think anyone in the U.S. thinks there is justification for Iran's achieving nuclear [weapons] capability," he said, without referring to Gates' reference to Israel's nuclear potential.

Olmert added, "We are not indifferent, cannot be indifferent, and won't be indifferent to efforts that appear serious to us, to develop capabilities that could be used as a springboard to build a [nuclear] bomb."

Gates told the Senate committee that the U.S. could not guarantee that if Iran acquires a nuclear weapon, it would not attack Israel with it. "I don't think that anybody can provide that assurance," he said.