The truce, which was announced Sunday, came about because of new international pressure after the war in Iraq. But its roots are deeper than that, in the complex politics of Palestinian violence, which fed the 33-month-old uprising against Israel and now might, haltingly, be bringing it to a close.

Mahmoud Abbas, the Palestinian prime minister, has set a trap for Hamas and other militant groups. He is hoping to whipsaw any relative calm resulting from a cease-fire to extract concessions from Israel, like the opening of military checkpoints inside Gaza today. Then he wants to use the political support he hopes will follow to comply with the international peace plan known as the road map, collecting weapons and punishing whoever violates the truce, his advisers say. He has made no secret that his goal is to turn Hamas into just another political party, stopping it from conducting in effect its own foreign policy toward Israel. 

Hamas leaders see the trap clearly. That is why they called for Mr. Abbas's resignation earlier this month, after he urged an end to the armed uprising against Israel. 

Hamas leaders are gambling that the cease-fire will fail and with it, Mr. Abbas and the American-led peace plan, say Palestinian officials who have negotiated with them. Hamas hopes Mr. Abbas's own trap will close over him, the conflict will resume and a negotiated solution will seem more hopeless than ever.

As the cease-fire negotiations ripened last week, Nabil Shaath, the Palestinian foreign minister, acknowledged in an interview that bad faith was a key. "Everybody is bargaining with a very different set of expectations," he said. "Maybe Hamas didn't want to go into a situation against its interests, but they bet that Israel will not follow through."

The question is why Hamas feels it must play along with the governing Palestinian Authority even for a short time. There are two sets of motivations cited by Palestinian officials and militant leaders. One arises from external considerations and the other, subtler one, from intensely factionalized Palestinian politics.

The American defeat of Saddam Hussein played a central role, as Hamas sponsors in Syria and Iran came under new American pressure and Arab governments, including Saudi Arabia's, moved to calm the region. "After Sept. 11, the Palestinian resistance lost its international support," said Samir al-Mashharawi, a top official here of Mr. Abbas's mainstream Fatah faction. "After the Iraq war, the Palestinian resistance lost its Arab support."

Other motives stem from Palestinian politics. In the view of Mr. Abbas's allies and other Fatah officials, Fatah's initial leadership of the intifada, or uprising, legitimized Hamas violence. After the uprising began in September 2000, those officials noted, it was months before Hamas began playing a high-profile role. Now, with Fatah pursuing a truce, Hamas had little choice but to play along.

"Having Fatah involved made the conflict a national conflict," said Qadoura Fares, a Fatah legislator who negotiated the truce in Damascus, Syria, with leaders of Hamas and Islamic Jihad. "If Fatah is out, you have two extreme Muslim groups against Israel, against the peace process and against the Palestinian state. They understand these things."

Mr. Abbas is acting now because, along with the Palestinian people, Fatah is in trouble. Once Hamas joined fully in the fighting, Fatah found itself in a new competition for respect in the street. 

In the view of some of Mr. Abbas's advisers, the great mistake made then by Yasir Arafat, the Palestinian leader, was to try to out-Hamas Hamas. That was an impossible proposition for Fatah, given its official acceptance of a two-state solution with Israel.