The officials said that as a result of the changed thinking about Palestinian abilities, they had come to accept the cease-fire that the Palestinian prime minister, Mahmoud Abbas, negotiated last month with Hamas and other Palestinian groups.

In June, when the cease-fire was negotiated, it was belittled by Israeli and American officials as a poor substitute for tough actions against militants. Lately, as attacks on Israelis have declined and support for Mr. Abbas among Palestinians seems to have grown, Americans have changed their tone.

"Both sides now think the cease-fire is a good idea and the early Israeli skepticism has changed," a senior administration official said, referring to Israeli and Palestinian positions. He said one advantage of the cease-fire was to give Mr. Abbas time to build up and consolidate his security forces for a campaign against militant groups. 

The cease-fire is supposed to last only three months. The United States is urging Israel to improve conditions in Palestinian areas so there would be overwhelming popular pressure in the West Bank and the Gaza Strip to continue the cease-fire for at least another three months.

In this period, American officials say, they hope to speed as much as $300 million in aid for the Palestinian Authority, channeled through the Central Intelligence Agency, to replace everything from jails to communication equipment to vehicles destroyed in the last two years by Israeli armed forces.

Officials, who spoke on the condition on anonymity, said the administration's thinking on the issue of the cease-fire was discussed this week when Prime Minister Ariel Sharon of Israel met with President Bush at the White House, and last week during a visit by Mr. Abbas.

Mr. Abbas and his security director, Muhammad Dahlan, have appealed to American officials on the issue of taking on militant groups, American officials said, arguing that the Palestinian security forces are splintered, with many members remaining loyal to Yasir Arafat, the Palestinian leader, with whom Washington refuses to deal.

"We've emphatically stated in public and private what needs to be done," a senior American official said. "It is clear that it cannot be done instantly. It requires planning, a strengthening of security forces and a unification of those forces under Abbas and Dahlan."

To create what the official called "political space" for Mr. Abbas to build up his popularity and strengthen his command of his forces, American officials say the United States must quietly continue to urge Israel to improve Palestinian conditions and meet other Palestinian requests. To this end, American and Israeli officials named two task forces after the meeting on Tuesday between Mr. Bush and Mr. Sharon, administration officials said. 

The first task force is to deal with the barrier being built by Israel in the West Bank, cutting off Jewish settlements from Palestinian areas. Mr. Bush has said the barrier, while perhaps justifiable in security terms, is creating problems for the Palestinians that Israel needs to address.

After meeting with Mr. Bush, Israeli officials said that there remained a disagreement with the United States on the barrier — a patchwork of concrete wall, electric fencing and barbed wire — but that Israel would look for ways to add gates or take other actions to make it less onerous to the Palestinians.

An American official, going further, said today that the administration expected Israel to suspend construction of the barrier in those parts where it juts most sharply into Palestinian communities, cutting people off from their farms or homes.

The second task force created at the Bush-Sharon meeting, American officials said, was on the future of Israeli settlements throughout the West Bank and Gaza.

Under the peace plan presented to both sides earlier this year known as the road map, Israel is supposed to "freeze" all "settlement activity" in the first phase. Israel and the United States disagree on the meaning of those phrases, however.

Israel defines the freeze as a pledge to refrain from constructing housing except within the boundaries of existing settlements.

Washington regards such a definition as containing loopholes, in part because some settlement boundaries extend into vacant areas that could be used for more settlements.

In an interview published today with the Israeli newspaper Maariv, Secretary of State Colin L. Powell said Mr. Dahlan "must eliminate" the ability of Hamas and other groups to wage terrorist attacks. American officials say doing this would involve arresting large numbers of people and seizing arms.

But Mr. Powell also appeared to endorse Mr. Abbas's and Mr. Dahlan's stated concern that acting prematurely would ignite a civil war that their side might not be able to win. "We need to show a little bit of patience and flexibility to make sure that it happens in a way that does not result in a situation that undercuts or brings down Mahmoud Abbas, because then where are we?" Mr. Powell said.

The sticking point with Israel, as always, has to do with the Israeli government's insistence that it cannot take the steps desired by the United States without Mr. Abbas's forces taking some additional steps against the militants.

Israelis are demanding no less, said an official traveling with Mr. Sharon this week. "We have a public too in Israel," he said.

If not a total crackdown, Israeli officials are at least asking for actions including the shutdown of rocket factories in the Gaza Strip, a ban on Palestinians who are not in the regular security forces carrying weapons, and the arrest of anyone that Israel or the C.I.A. defines as planning a terrorist attack.

The fear in Israel, the senior Israeli official said, was based on evidence that Hamas and Palestinian Islamic Jihad were using it to "regroup and to arm themselves by smuggling weapons."

The United States is also asking Israel to take other steps to help Mr. Abbas, particularly the easing of closures and checkpoints in the West Bank and Gaza, the release of more prisoners and the dismantling of an estimated 100 settlement "outposts" built in the last two and a half years.

On these actions, as well, Israel says it cannot move without more action against Hamas and the militant groups. "We're trying to create a virtuous circle," an administration official said. "We're trying to make the judgment as to what at any given moment each side can do. We're constantly saying, 'What have you done for me lately?' "