JERUSALEM — Six months ago, after American intelligence agencies declared that Iran had shelved its nuclear-weapons program, the chances of a U.S. or Israeli military strike on Iran before President Bush left office seemed remote.
Now, thanks to persistent pressure from Israeli hawks and newly stated concerns by the International Atomic Energy Agency, the idea of a targeted strike meant to cripple Iran's nuclear program is getting a new hearing.
As Bush travels across Europe to gain support for possible new sanctions against Iran, Israeli leaders have been working to lay the psychological foundation for a possible military strike if diplomacy falters.
In public threats and private briefings with American decision-makers, Israeli officials have been making the case that a military strike may be the only way to thwart Iran's nuclear ambitions.
"Temperatures are rising," said Emily Landau, an Iran specialist at the Institute for National Security Studies, an independent Israeli research center.
Bush and Israeli Prime Minister Ehud Olmert have met twice in recent weeks for extended talks on Iran. America's intelligence chief, Mike McConnell, has traveled to Israel for private briefings, and Israeli Transportation Minister Shaul Mofaz publicly declared that a military strike on Iran may be "unavoidable."
In Germany on Wednesday, Bush said that "all options are on the table" if Iran doesn't abandon its uranium enrichment programs.
Iranian President Mahmoud Ahmadinejad greeted Bush's initiative by mocking the latest international efforts.
"They've tried by military threats ... and political pressure to stop you from your luminous path," Ahmadinejad reportedly told a rally in Iran on Wednesday. "But today they have seen that all their planning has failed.
"Today the Iranian nation is standing on the nuclear height."
Intelligence analysts disagree over the likelihood of a military strike on Iran before Bush leaves office. But there's little disagreement about the possible repercussions, which could include missile strikes on Israel, an attack on Saudi Arabian oil facilities, renewed attacks on Israel from Hezbollah fighters in southern Lebanon, a resurgence of Shiite Muslim resistance to U.S. forces in Iraq or an attack on oil shipping in the Persian Gulf, which could send crude oil prices well above $200 a barrel.
Some analysts view the latest Israeli threats as an attempt to put pressure on Iran to capitulate to Western demands. Other analysts see the Israeli campaign as intended to press the Bush administration to take the lead if the two nations decide to launch a military strike on Iran.
"The most likely scenario is that the Israelis will train and prepare as if they are very serious — and that's part of the bluff to get the U.S. engaged," said John McCreary, a retired intelligence analyst for the U.S. Department of Defense.
The key factor in any decision to launch a military strike is likely to be solid intelligence that Iran is rapidly advancing on its nuclear ambitions.
"I don't think there is that smoking gun that we can hold up and say that everyone should stand behind this," said Landau, who recently wrote an analysis titled "The Elusive Smoking Gun" for her think tank.
But Landau said the international debate had shifted in the weeks since the IAEA expressed "serious concerns" about Iran's nuclear ambitions and demanded more answers.
Israel already has demonstrated an ability to persuade reluctant Bush administration officials of the need to stage a pre-emptive strike. Before launching an airstrike on Syria last September, Israel provided the United States with intelligence suggesting that its Middle East neighbor was building a nuclear plant.
In April, the CIA publicly unveiled detailed images of the Syrian target and said that it was a nuclear reactor built with help from North Korea. Syria has denied the allegation. International inspectors are expected to visit the site for the first time later this month.
Considering Ahmadinejad's refusal so far to accept the international incentives, some analysts see support growing in Israel and the United States for a military strike.
"I think more and more people are looking to the military option as possibly the only thing that will work, and people are more and more feeling that negotiations won't work," said Meir Javendanfar, a co-author of "The Nuclear Sphinx of Tehran."
Hard-liners in the U.S. and Israel also dismiss the notion that U.S. or Israeli nuclear weapons would deter Iran from using such weapons itself if it succeeded in obtaining them.
The very fact that a military strike is percolating back into mainstream debate is a significant shift in the political discourse.
Most analysts dismissed the military option last December after U.S. intelligence agencies agreed that Iran had shelved its nuclear weapons work in 2003 and was unlikely to produce enough enriched uranium for a bomb until 2010 or 2015.
Though Bush and Olmert challenged the assessment at the time, the analysis made it more difficult to make a case for swift military action.
Since then, Israel has shared more of its intelligence with the Bush administration.
Last week, Olmert traveled to Washington for extended talks with Bush that focused primarily on Iran.
"Every passing day the world acts, under the leadership of the United States, to achieve that goal that will prevent Iran's armament," Olmert said after meeting Bush.
On Wednesday, Olmert spokesman Mark Regev said that Iran must understand that it must give up its nuclear ambitions in order to receive international incentives.
"Only if they understand that there is a clear and stark choice, that there isn't wiggle room, only then can diplomacy succeed," Regev said. "I think in dealing with the Iranians it's important to have both carrots and sticks."