Pakistan's President Pervez Musharraf is supposedly a key U.S. ally in the "war on terror." But is he, in fact, more of a liability than an asset in combating Al Qaeda and the increasingly menacing Taliban forces in Afghanistan?

Since 9/11, the Bush administration has been propping up Musharraf's military regime with $3.6 billion in economic aid from the U.S. and a U.S.-sponsored consortium, not to mention $900 million in military aid and the postponement of overdue debt repayments totaling $13.5 billion. But now the administration is debating whether Musharraf has become too dependent on Islamic extremist political parties in Pakistan to further U.S. interests, and whether he should be pressured to permit the return of two exiled former prime ministers, Benazir Bhutto and Nawaz Sharif, who have formed an electoral alliance to challenge him in presidential elections scheduled for next year.

Musharraf's most vocal defender is former Deputy Secretary of State Richard Armitage, who has urged continued support for him "no matter how frustrated we become at the pace of political change and the failure to eliminate Taliban fighters from the Afghan border." Musharraf is better than what might come after him, Armitage argues, and is a moderate who has done his best to fend off the entrenched forces of Islamic extremism in Pakistan.

But this argument does not hold up against mounting evidence that, as an ally, Musharraf has been an opportunist from the start who has continued to help the Taliban (just as he had done before 9/11 ) and who has gone after Al Qaeda cells in Pakistan only to the extent necessary to fend off U.S. and British pressure.

On Sept. 19, 2001, Musharraf made a revealing TV address in Urdu, not noticed at the time by most Americans, in which he reassured Pakistanis who sympathized with Al Qaeda and the Taliban that his decision to line up with the U.S. was a temporary expedient.

To Taliban sympathizers, Musharraf directed an explicit message, saying: "I have done everything for the … Taliban when the whole world was against them….We are trying our best to come out of this critical situation without any damage to Afghanistan and the Taliban." He has kept his promise to the latter.

Taliban forces continue to have unrestricted access to Pakistani border towns as staging areas and sanctuaries. Pakistani soldiers look the other way when Taliban units cross the mountains at Bormoi. With U.S. and NATO forces in Afghanistan suffering increasingly heavy casualties in the face of a Taliban offensive this summer, their officers no longer mince words about Pakistan's role. Col. Chris Vernon, chief of staff of British forces in southern Afghanistan, charged recently that the Pakistan border town of Chaman serves as the "major headquarters" for a guerrilla network in southeast Afghanistan.

Musharraf sees the Taliban as a pro-Pakistan counterweight to Indian influence in Afghanistan and wants to keep it strong in case Afghan President Hamid Karzai is overthrown and Afghanistan collapses into chaos. As a sop to Washington and London, he ordered raids on two small Taliban encampments in July, and he occasionally rounds up key Al Qaeda figures — but in many cases only after the FBI and CIA have confronted Pakistani police with communications intercepts pinpointing their hide-outs.

Even if Musharraf wanted to remove Taliban and Al Qaeda forces from Pakistan, his ability to do so is limited by the political pact that he made with a five-party Islamic alliance in 2004 to win state elections in the two key border provinces. As a result, Al Qaeda and Taliban activity is openly supported by local officials there, and Pakistani groups allied with Al Qaeda are thriving, notably Jaish-e-Muhammad and Lashkar-e-Taiba. This prevents Musharraf from carrying out his pledge to crack down on madrasas (religious schools) linked to terrorist groups.

The Islamic parties are flourishing under the protective umbrella of the Pakistani armed forces. Their growth would be slowed if secular political forces had a chance to assert themselves through free elections and a parliamentary system liberated from army manipulation. Under Musharraf, the army has seized much more power than past military regimes, installing military officers in hundreds of government posts previously held by civil servants. Army-sponsored conglomerates control multibillion-dollar enterprises and will not be easily dislodged. As a Pakistani editor commented, "Most countries have an army, but in Pakistan, the army has a country."

The U.S. should use its aid leverage to promote three goals: Bhutto and Sharif should be permitted to return and organize freely. If Musharraf wants to run for president again, he should step down as army chief of staff and run as a civilian. Finally, he should turn over power to a neutral caretaker government that would conduct the elections. This would be welcomed in Pakistan even by elements within the armed forces. An open letter in July from a group of retired generals called for "the disengagement of the military from political power." As one of its signatories, Lt. Gen. Talat Masood, observed, "There is a genuine urge and demand in the country to revert to democracy and give a fair deal to all the parties."

SELIG S. HARRISON, director of the Asia program at the Center for International Policy and a senior scholar at the Woodrow Wilson International Center for Scholars, is a former South Asia bureau chief for the Washington Post.