KABUL, Afghanistan — Relations between the U.S. military and the Pakistani army, critical allies in the "war on terror," are at their worst point since Sept. 11, 2001, senior Western military officers and diplomats here say, as Pakistani troops withdraw from several tribal areas bordering Afghanistan that are home to Taliban and al-Qaida leaders and thousands of their fighters.

Gen. Ashfaq Kiyani, chief of the Pakistani army, has told U.S. military and NATO officials that he will not retrain or re-equip troops to fight the counterinsurgency war the Americans are demanding on Pakistan's mountainous western border.

Instead, the bulk of the army will remain deployed on Pakistan's eastern border and prepare for possible conflicts with traditional enemy India — wars that have always been fought on the plains of Punjab. More than 80 percent of the $10 billion in U.S. aid to Pakistan since the Sept. 11 attacks has gone to the military; much of it has been used to buy expensive weapons systems for the Indian front rather than the smaller items needed for counterinsurgency.

There are also signs that Washington is delaying delivery of U.S. arms meant for the eastern front and is asking Western allies to do the same.

In recent weeks, Islamic militants in Indian Kashmir, restrained by Islamabad since Pakistan and India conducted peace talks in 2004, have revived their attacks against Indian forces. Extremist bombings in Jaipur, India, on May 14 killed more than 80 people. Relations between India and Pakistan have improved dramatically in recent years, but tensions could again escalate.

Pakistani army officials have told Washington that they will continue to deploy the Frontier Corps and other paramilitary units along the long, porous border with Afghanistan, but they are poorly equipped, badly trained and have lost every major engagement with militants so far. The U.S. military is training and equipping these nearly100,000 troops but has rejected Pakistani requests to equip four to five new units.

The Taliban virtually rules the seven tribal agencies that make up the Federally Administered Tribal Areas. Growing frustration among U.S. and NATO forces in Afghanistan has led to a crescendo of calls by U.S. and Afghan officials, NATO officers, European leaders and the United Nations urging Pakistan to continue supporting the fight against extremism.

But the Pakistani army is shaken. It has lost more than 1,000 paramilitary and other soldiers since its first offensive against the Taliban in 2004. Recently, it has reached unofficial peace deals with Pakistani and Afghan Taliban leaders in the tribal areas in which they have promised not to attack Pakistani forces.

These deals do not stop the Taliban from attacking NATO and Afghan forces in Afghanistan. Taliban attacks from Pakistan into Afghanistan have risen dramatically this spring; in April, incidents spiked to more than 100 a week, up from about 60 a week in March.

One effect of the peace deals became clear last month, when 30 journalists were invited to an unprecedented news conference in South Waziristan with Baitullah Mehsud, leader of the Pakistani Taliban and the main host for Afghan Taliban and al-Qaida leaders in the tribal areas. Journalists saw few signs of the military, with the Taliban occupying army posts that had been abandoned.

Mehsud vowed that "jihad in Afghanistan will continue" and declared that "Islam does not recognize any manmade barriers or boundaries." Last month, a Taliban Web site called for a general uprising in Afghanistan "till the withdrawal of the last crusading invader."

Early victims of the Pakistani army's strategic shift are the civilian governments of Pakistan and Afghanistan. Afghan President Hamid Karzai, who is under severe international pressure to improve governance and fight corruption, told me during a long conversation that he was deeply frustrated by Pakistan's attitude. "We have to succeed in convincing the world to end the sanctuaries for terrorism," Karzai said.

It was hoped that after elections in February ended nine years of military rule, Pakistan's civilian government would take charge of foreign policy and persuade the army to share national security policy toward India and Afghanistan. But the government has been plagued by problems and is paralyzed on several fronts.

The major powers should engage Pakistan's army to learn whether its new policy represents a strategic shift away from the international fight against terrorism. India must be persuaded to do more to resolve the Kashmir issue, and the world must help strengthen Pakistan's civilian government, especially in the face of its severe economic problems. Getting the army back on track to fight extremism is vital if Pakistan is not to be swamped by Taliban-style rule and become a haven for al-Qaida.

Ahmed Rashid is a Pakistani journalist and author of "Descent Into Chaos: The United States and the Failure of Nation Building in Pakistan, Afghanistan and Central Asia." He wrote this commentary for The Washington Post.