HERZLIYA, Israel -- Prime Minister Ariel Sharon said Thursday that Israel was willing to move some Jewish settlements in the West Bank and Gaza Strip but delivered an ultimatum that Palestinians had only a few months to make peace or Israel would impose its own solution. The White House credited Sharon with taking significant steps toward peace but criticized any go-it-alone moves by Israel that would undercut negotiations on a U.S. "road map" peace plan to create a Palestinian state by 2005. Under Sharon's "disengagement plan," Israel would pull back from some of the area it conquered in the 1967 Mideast War and relocate some settlements to create a more easily defended security boundary and reduce the number of Israelis in Palestinian areas.
Israel would also speed up construction of a contentious barrier of fences, walls and trenches, whose planned path dips deep into the West Bank.
"This reduction of friction will require the extremely difficult step of changing the deployment of some of the settlements," Sharon said, without naming the settlements that would be taken down.
Sharon's plan, which he unveiled in a speech to a security conference in the Tel Aviv suburb of Herzliya, came in the face of intense domestic pressure to take action to end the violent conflict that has unnerved Israelis and badly damaged the economy over the past three years.
The prime minister's popularity has plummeted in recent months as the U.S. "road map" peace plan stalled amid continuing bloodshed and intransigence on both sides.
The idea of a forced partition also reflects Israeli concerns about demographic projections that Arabs will, within a few years, outnumber Jews in the area currently controlled by Israel.
Sharon said Israel remained committed to the road map, but demanded Palestinians begin dismantling militant groups, as called for by the road map, or face an Israeli-imposed plan.
"We are interested in conducting direct negotiations, but do not intend to hold Israeli society hostage in the hands of the Palestinians. ... We will not wait for them indefinitely," Sharon said. "If there is no progress toward peace in a matter of months, "then Israel will initiate the unilateral security step of disengagement from the Palestinians," he said.
Sharon said the boundary would not be a permanent, political border: "The disengagement plan is a security measure and not a political one."
Under this approach, Sharon said, the Palestinians would receive "much less" territory than they would have received from direct negotiations.
He also said all his moves would be coordinated with the United States.
Israel also would reduce travel restrictions that have crippled the Palestinian economy over the past three years, promising to end closures, curfews and roadblocks and to transfer some areas to Palestinian control, Sharon said.
Palestinian Prime Minister Ahmed Qureia said he was confident the two sides could reach rapid agreement for a Palestinian state, but he bristled at Sharon's threats.
"These are ultimately dangerous words, and this type of talk is simply not acceptable," Qureia told The Associated Press.
U.S. officials have joined Palestinians in condemning any Israeli-imposed measures -- certain to leave Palestinians with less land than they want -- saying that only a deal acceptable to both sides can lead to peace.
"We would oppose any unilateral steps that block the road toward negotiations under the road map," White House press secretary Scott McClellan said Thursday. "The United States believes that a settlement must be negotiated and we would oppose any effort -- any Israeli effort -- to impose a settlement."
However, the White House found much to like in Sharon's speech as well, with McClellan singling out for praise Sharon's "strong reiteration of his support for the road map as the way forward" and his statement that unauthorized outposts will be dismantled.
"We are also pleased that for the first time he said flatly that there will be no new settlements, no confiscation of land for construction, no special economic incentives for settlers and no construction beyond present construction zones," McClellan said.
Israeli Justice Minister Yosef Lapid said he believes Sharon will give the Palestinians three months to begin complying with the road map before imposing his new plan.
Lapid, of the centrist Shinui Party, said Sharon's talk of moving some settlements was "a major breakthrough."
Sharon was a chief architect of Israel's settlement policy over his three-decade political career, and any steps to dismantle or move settlements would be a revolutionary step for him that could fracture his hard-right governing coalition.
"We will not be part of a government that uproots Jewish communities and will defame the entire Zionist enterprise," said Housing Minister Effie Eitam, leader of the National Religious Party.
On the other side of the Israeli political spectrum, Labor Party leader Shimon Peres said he too was disappointed with the speech.
"I am very frustrated," he told Israeli Television. "In the speech we heard, there is nothing new."
Sharon's speech comes after weeks of buildup. Sharon began speaking of undefined "unilateral steps" last month, indicating he might consider moving West Bank Jewish settlements while seizing control of swaths of the West Bank.
Palestinian and U.S. officials have called on Israel to stick to the road map, which envisions an independent Palestinian state by 2005. In the interim, it requires Israel to freeze settlement activity and calls on the Palestinians to dismantle militant groups -- steps neither side has taken.
Israel has some 150 settlements in the West Bank and Gaza, with about 220,000 Jewish settlers. Roughly 3.5 million Palestinians live in the occupied areas.
West Bank settlers called Sharon's speech a "plan of illusions that will escalate terror."
"The dismantling of settlements and expulsion of Jews from their homes will only increase the appetite of the murderers and will bring about the destruction of Zionism," said settler spokesman Yehoshua Mor-Yosef.
Islamic militants said the speech amounted to a victory for their attacks that have killed roughly 900 Israelis in the past three years.
"This is a new language by the Israelis, and this is an evidence that the uprising has created a new fact on the ground," said Sheik Nafez Azzam, an Islamic Jihad leader.
Violence continued early Thursday, as Israeli troops killed at least four Palestinians in the West Bank city of Nablus.
The army moved into the city's ancient bazaar quarter before dawn in a search for wanted Palestinian militants, a military spokeswoman said. Palestinian security sources said one of the dead was unarmed.
The military said one man ran toward troops with an explosive device and was shot as he approached, while in a separate incident, three masked men with automatic weapons shot at soldiers from a rooftop and were killed by return fire. The army also reported 10 arrests, including two people it said were planning suicide attacks.