Israeli officials say they won't warn the U.S. if they decide to launch a pre-emptive strike against Iranian nuclear facilities, according to one U.S. intelligence official familiar with the discussions. The pronouncement, delivered in a series of private, top-level conversations, sets a tense tone ahead of meetings in the coming days at the White House and Capitol Hill.

Israeli officials said that if they eventually decide a strike is necessary, they would keep the Americans in the dark to decrease the likelihood that the U.S. would be held responsible for failing to stop Israel's potential attack. The U.S. has been working with the Israelis for months to convince them that an attack would be only a temporary setback to Iran's nuclear program.

Israeli Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak delivered the message to a series of high-level U.S. visitors to the country, including the chairman of the Joint Chiefs of Staff, the White House national security adviser, the director of national intelligence and top U.S. lawmakers, all trying to close the trust gap between Israel and the U.S. over how to deal with Iran's nuclear ambitions.

Netanyahu delivered the same message to all the Americans who have traveled to Israel for talks, the U.S. official said.

The official spoke on condition of anonymity to discuss sensitive strategic negotiations.

The White House did not respond to requests for comment. The Pentagon and Office of Director of National Intelligence declined to comment, as did the Israeli Embassy.

Iran claims its nuclear program is for peaceful purposes, but the International Atomic Energy Agency has raised alarms that its uranium enrichment program might be a precursor to building nuclear weapons. The U.S. has said it does not know whether the government has decided to weaponize its nuclear material and put it on a missile or other delivery device.

The secret warning is likely to worry U.S. officials and begin the high-level meetings with Israel and the U.S. far apart on how to handle Iran.

But the apparent decision to keep the U.S. in the dark also stems from Israel's frustration with the White House. After a visit by National Security Adviser Tom Donilon, they became convinced the Americans would neither take military action, nor go along with unilateral action by Israel against Iran.

The Israelis concluded they would have to conduct a strike unilaterally - a point they are likely to hammer home in a series of meetings over the next two weeks in Washington, the official said.

Barak will meet with top administration and congressional officials during his visit. Netanyahu arrives in Washington for meetings with President Barack Obama next week.

The behind-the-scenes warning belies the publicly united front the two sides have attempted to craft with the shuttle diplomacy to each other's capitals.

"It's unprecedented outreach to Israel to make sure we are working together to develop the plan to deter Iran from developing a nuclear weapon," and to keep Iran from exporting terrorism, said Maryland Rep. Dutch Ruppersberger, the top Democrat on the House intelligence committee.

He traveled there with the intelligence committee chairman, Rep. Mike Rogers, R-Mich., to meet Israel's prime minister and defense minister, along with other officials.

"We talked about the fact that sanctions are working and they are going to get a lot more aggressive," Ruppersberger added.

They also discussed talked about presenting a unified front to Iran, to counter the media reports that the two countries are at odds over how and when to attack Iran.

"We have to learn from North Korea. All those (peace) talks and stalling and they developed a nuclear weapon," he said. "We are going to send a message, enough is enough, the stalling is over. ... All options are on the table."

Rogers said on Monday: "I got the sense that Israel is incredibly serious about a strike on their nuclear weapons program. It's their calculus that the administration ... is not serious about a real military consequence to Iran moving forward."

"They believe they're going to have to make a decision on their own, given the current posture of the United States," he added.

U.S. intelligence and special operations officials have tried to keep a dialogue going with Israel despite the high-level impasse, offering options such as allowing Israel to use U.S. bases in the region to launch such a strike, as a way to make sure the Israelis give the Americans a heads-up, according to the U.S. official and a former U.S. official with knowledge of the communications.

Cooperation has improved on sharing of intelligence in the region, according to one current and one former U.S. official. Israel is providing key information on Syria, for instance, now that the U.S. has closed its embassy and pulled out its diplomats and intelligence officials stationed there, the U.S. official said.