ISLAMABAD, Pakistan - Pakistan ordered its army yesterday to go after the country's top Taliban commander, a feared militant whose remote stronghold could prove a difficult test for troops but whose demise would be a major blow to the insurgencies here and in Afghanistan.

The announcement in South Waziristan, rumored for weeks, came hours after a suspected U.S. missile strike killed five alleged militants there. The move will likely please Washington, which considers the tribal region a particularly troublesome hideout for al-Qaeda and Taliban fighters implicated in attacks on U.S. troops in Afghanistan.

Owais Ghani, the governor of North West Frontier province, told reporters in Islamabad yesterday that the government felt it had no choice but to resort to force against Pakistani Taliban chief Baitullah Mehsud and his network. Past army action in the region had usually faltered or ended in truces, strengthening the militants.

"Baitullah Mehsud is the root cause of all evils," Ghani said, noting a slew of suicide bombings that have shaken Pakistan in recent days. "The government has decided that to secure the innocent citizens from terrorists, a meaningful, durable, and complete action is to be taken."

South Waziristan, part of Pakistan's semiautonomous tribal belt, is a rumored hideout of Osama bin Laden. As the military has pursued a separate offensive against Taliban fighters in the northwest's Swat Valley, observers have noted that the Taliban will not be defeated in Pakistan unless it loses its tribal sanctuaries.

The United States has frequently targeted South Waziristan with missile strikes. The suspected strike yesterday hit three vehicles and killed five suspected militants. Two Pakistani intelligence officials confirmed the attack on condition of anonymity because they were not authorized to speak to reporters.

Mehsud is believed to pose a serious internal threat to the Pakistani government, and he has been blamed for the killing of former Prime Minister Benazir Bhutto, though he has denied that accusation. The Taliban chief also has been linked to bombings on both sides of the Afghanistan- Pakistan border.

In many ways, a full-scale battle in South Waziristan will be a harder fight than in Swat, where the army claims to have killed hundreds of militants over the last six weeks.

Pakistan's decision comes as public opinion has shifted against the Taliban, which has been blamed or has claimed responsibility for a series of bloody attacks in recent weeks, including one that killed a prominent anti-Taliban cleric and another that devastated a luxury hotel in Peshawar.

Yesterday, a bomb rocked a market in the northwestern town of Dera Ismail Khan, while officials said clashes between the Taliban and security forces killed at least 20 militants in a tribal area supposedly cleared of insurgents months ago.