The death of Sheik Ahmad Yassin will pave the way to Palestinian moderation, Israel and its friends in Washington say.
But others, including Bush administration officials, are worried that the road just got a lot bumpier.
The United States scrambled Monday to reassure the world -- and particularly Hamas -- that it had no foreknowledge of Israel's predawn assassination of the Hamas leader in Gaza.
"The consequences of this action, in terms of raising tension and making it harder to pursue peace efforts -- those are things of concern to us," said State Department spokesman Richard Boucher, calling the killing "deeply troubling."
The White House ultimately concurred, after initially affirming Israel's right to defend itself.
The law of unintended consequences, which has dogged other recent major Israeli initiatives, had struck again: An attempt to stem terrorism instead had sparked in Washington and European capitals a fear of revenge attacks.
Administration insiders described Monday as a day in which Boucher started by contemplating a mild rebuke, then toughening it as European and Arab countries expressed alarm and concern that the attack would strengthen Hamas and not weaken it.
"It's like a starfish: You cut off one leg, another grows in," one administration official said. "We're expecting alerts to go up everywhere."
By Tuesday, CNN was quoting an Iraqi cleric as calling on Muslims to "unite against Israel," raising the prospect that Yassin's killing could hinder U.S. efforts to disengage from Iraq by sparking more violence there.
After Hamas reportedly threatened to broaden its attacks beyond Israeli targets, European Union foreign ministers said in a statement that the killing "has inflamed the situation."
Kofi Annan, U.N. secretary general, "strongly condemned" the killing and said he was worried that "such an action would lead to further bloodshed and death and acts of revenge and retaliation."
The U.N. Security Council called a meeting to discuss the assassination.
Especially aggravating, U.S. officials said, was the prospect that the assassination would scuttle the possibility of a new peace initiative from next week's Arab League summit.
American officials also were frustrated because they see the attack as undermining support for Prime Minister Ariel Sharon's plan for unilateral withdrawal from the Gaza Strip and part of the West Bank, which they support.
Israeli Foreign Minister Silvan Shalom had planned to spend Monday in Washington describing plans for the withdrawal and probing U.S. proposals to contain Syria and Iran. Instead, much of his time was spent explaining the Yassin killing.
A senior Israeli official traveling with Shalom said the concerns about destabilization in the region were unfounded. The Palestinian Authority is well equipped to deal with Hamas, the official said, noting that the authority has 22,000 men under arms in the Gaza Strip, as opposed to about 1,000 loyal to Hamas.
"Whatever the pictures show you -- the protests, the riots -- it won't influence what's happening in Gaza," he said.
Israel's friends on Capitol Hill agreed. Democrats, mindful of election-year pressure to outflank President Bush on support for Israel, took the initiative.
Democratic presidential candidate Sen. John Kerry of Massachusetts was on vacation, but a spokesman said Yassin's history couldn't be ignored. "It's important to remember that Sheik Yassin was responsible for organizing dozens of deadly terror attacks in Israel," Mark Kornblau said.
Democratic Reps. Eliot Engel and Anthony Weiner of New York and Shelley Berkley of Nevada issued statements supporting the strike on Yassin. Sen. Hillary Clinton (D-N.Y.) told a United Jewish Communities gathering Tuesday in Washington that Americans should stand up for Israel's right to defend itself, "including going after those who direct" terrorism.
Officials at pro-Israel groups minimized the administration criticism and said they didn't expect it to last.
"The administration is even more concerned than the Israelis that the disengagement go through and that Hamas not take control of Gaza, and any action the Israelis take to prevent that happening, they support," said one pro-Israel official based in Washington.
"The more the leaders of Hamas are running for cover," the official said, "the less likely they are to be undermining someone like Mohammed Dahlan," a former P.A. security official and a relative moderate in Gaza.
Efraim Halevy, a former chief of Israel's Mossad intelligence agency, said moderate Arab nations might suffer unrest in the short run but also would benefit down the road.
"The less leaders there are who support and who champion violence as a method of pushing policy, the more the chance there will be more moderation in the region," Halevy told reporters Tuesday in a conference call.
Halevy also said concerns that Hamas would now aim attacks at U.S. targets were unfounded, because such attacks would open the group up to direct U.S. retaliation. "It would expose Hamas to the kind of pressures it has not had until now," he said.
Malcolm Hoenlein, executive vice chairman of the Conference of Presidents of Major American Jewish Organizations, said he expected the criticism to dissipate, especially given U.S. actions to pursue Al Qaeda leaders.
"It should not be troubling that we go after Yassin," he said. "Then we would have to be troubled by the effort on the Pakistan-Afghanistan border to go after Osama bin Laden."
Some analysts wondered if Sharon was losing control of events.
"Is Sharon once again being the great tactician and the terrible strategist?" asked David Mack, a vice president at the Middle East Institute and former assistant deputy secretary of state for Near East affairs.
It's a charge that Sharon has fought for decades. Fairly or not, he is known as the general whose tactical brilliance won crucial battles in the 1973 Yom Kippur War, and the defense minister who plunged Israel into a strategic morass in Lebanon in 1982.
Whatever Sharon's intentions when he announced his plan to uproot settlements and leave Gaza and parts of the West Bank, they have been overtaken by the intentions and actions of others.
The United States is pressing Israel hard for far-reaching concessions in the West Bank, as well as Gaza; the Palestinian Authority is seeking to build bridges to Hamas and Islamic Jihad, terrorist organizations that Israel reviles, and Egypt wants to rewrite the 1978 Camp David peace accords, a precedent Israel wants to avoid at all costs.
Part of Sharon's problem, associates said, is his penchant for playing his cards so close to his chest. Only three or four officials are privy to what shape the withdrawal will take. Members of Sharon's Cabinet who have been kept in the dark say such steps are far-reaching and require consultation.
"It's very unusual that the prime minister is pushing forward a plan in Washington that the prime minister did not bring to Cabinet, to the coalition," Housing Minister Effi Eitam said in an interview last week in Washington, where he was lobbying against the withdrawal. "It is totally improper as far as how a democratic country should be handled."
A similar secretiveness by Sharon in plotting Israel's security barrier last year led to a breakdown in U.S.-Israel communications. The resulting friction was behind the U.S. refusal to appear on Israel's behalf when Palestinians brought the fence issue to the International Court of Justice in The Hague in February.
Sharon has promised a finalized withdrawal plan in time for an April 14 summit with Bush. Sharon's bureau chief, Dov Weisglass, is in Washington this week for another round of talks with U.S. officials, discussions that have been shuttling back and forth between Washington and Jerusalem since early February.
It's an open question whether Sharon will meet the deadline. American officials and others have expressed frustration with the vagueness of the proposals so far.
"What are the parameters?" David Satterfield, deputy assistant secretary of state for Near East affairs, said at the Israel Policy Forum recently. "Not just for Gaza, but for the West Bank, for the separation barrier. What's out there?"