ISLAMABAD -- Pakistan edged closer Sunday to a major conflict with Taliban militants as a controversial peace deal with Islamic extremists in the Swat valley near the Afghan border began to unravel, according to military officials and politicians.

The confrontation comes as President Asif Zardari is scheduled to arrive Tuesday in Washington, where he'll meet President Barack Obama and hold trilateral talks with U.S. and Afghan political leaders. Last month, Secretary of State Hillary Clinton accused Pakistan of ''abdicating to the Taliban,'' but in recent days the country's security forces have battled militants in parts of the troubled Northwest Frontier Province, though not in the militants' new stronghold of Swat.

The Obama administration has grown increasingly alarmed by the militants' advance, which if it continues could threaten a crucial U.S. supply route to Afghanistan, and by the Zardari government's efforts to fight the militants in some places while negotiating with them in others.

The administration, however, is also divided about both the causes of Pakistan's tentative responses to what Defense Secretary Robert Gates on Sunday called ''an existential threat,'' and about possible solutions to it.

Administration officials held a high-level meeting Saturday at the National Defense University in Washington to review their Afghan strategy.

Some officials blame Zardari and advocate reaching out to his main political opponent, Nawaz Sharif, but others distrust Sharif, who has ties to a number of Islamist groups and to Saudi Arabia.

Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, blames Pakistan's civilian leaders rather than the military for the indecisiveness. But others think that the military has been unable or unwilling to accept the fact that Islamic militancy, not Hindu-dominated India, is now the country's main enemy.

Violence erupted in Swat over the weekend, following weeks of relative calm after Pakistani officials negotiated a peace accord with the insurgents in mid-February. Pakistani forces have been battling militants first in Dir and then in Buner districts, which are on either side of Swat, since April 26, but a delicate truce had held in Swat.

The bodies of two armed forces personnel were found Sunday, their heads severed and their bodies mutilated, in the Khwazakhela area of Swat.

Kidnapped several days earlier while they were on leave, the army soldier and paramilitary trooper bore marks of severe torture, according to a security official, who couldn't be named because he's not authorized to speak to the media.

Separately, militants blew up a school in the Kabal area of Swat and attacked the electric grid station in the district's main town of Mingora.

Officials said that Taliban were openly patrolling the streets of Mingora with their weapons, in violation of the peace deal. Authorities imposed a curfew in Mingora Sunday night.

''The militants have completely gone back on their pledges. They don't want peace, they just want an autonomous state,'' said the security official. "They are a menace. They have to be taken on, no matter how big the challenge.''

BY SAEED SHAH, McClatchy News Service, May 4, 2009