Israel killed off more than just the second-most popular Palestinian leader with a missile strike on Monday.
It also finally finished off President Bush's already tattered road map for creating a Palestinian state, a plan that was essential to his vision of a terror-free Middle East.
And by assassinating - rather than simply arresting and trying the Islamic leader of the group Hamas - Sheikh Ahmed Yassin, Israel further erodes its role as a model of democratic and civil principles to the Arab world.
At a strictly tactical, military level, Israel probably bought itself some relief from the horror of suicide bombings by killing Mr. Yassin. His absence will temporarily weaken a group that both wages war on Israel's existence by killing civilians while also providing social services to Palestinians. A wave of such targeted killings against Hamas leaders and others in 2003 did at first reduce the number of suicide bombings against innocent Israelis.
But the bombings have since continued apace. And so, in a short-term way, Prime Minister Ariel Sharon is doing what many Israelis expect of him: Defending them - for a while.
And Mr. Sharon may also hope that a lull in terrorist attacks will allow him to go ahead with a plan to withdraw the Israeli presence from the Gaza Strip to avoid an Arab perception that Israel would be retreating as a result of suicide bombings. That plan could be part of a Sharon idea for a Palestinian state - one that's subservient, small, and scattered.
But Sharon's decision to kill Yassin has put any such ideas on hold as both Bush and the Palestinian Authority's Yasser Arafat try to deal with the blowback.
For an already weak Mr. Arafat, the inevitable rise of popularity for Hamas after this killing will further diminish his influence and probably bring more chaos to Palestinian areas. For Bush, Arab anger over the assassination will hinder his recent initiative to nurture political reform within Arab states. Just how the president responds to this killing will send a signal on how the US plans to deal with other groups like Hamas in the Islamic world that attract followers through both social work and militancy.
Bolder action than the road map is now needed from the US to lift Israel out of its defense-only strategy, despite any reluctance to twist Israel's arm in an election year.
If Bush really wants to be a "war president," he must also be on a peace footing in waging an effective diplomatic campaign that will both safeguard Israel and assure Palestinians of a state.