By Pir Zubair Shah, Sabrina Tavernise and Mark Mazzetti

ISLAMABAD, Pakistan  American and Pakistani officials said Friday they were increasingly convinced that an American drone strike two days earlier had killed Baitullah Mehsud, Pakistan’s enemy No.1 and the leader of its feared Taliban movement.

While Mr. Mehsud was a pivotal figure who held together the loose and disparate network of militants in Pakistan, experts said his death would not end the violent Taliban insurgency, its ties to Al Qaeda or its push for Pakistani territory.

Mr. Mehsud, a militant in his 30s who made attacks inside Pakistan his top priority, was blamed for the assassination of the former prime minister, Benazir Bhutto, and scores of suicide bombings, including at the Marriott Hotel in Islamabad, which killed more than 50 people last September.

The drone attack was the result of months of closer cooperation by the Pakistani and American intelligence agencies. But his death would raise questions about how far the Pakistani authorities are now willing to go to crush the remnants of the Pakistani Taliban  and how hard the Obama administration would continue to push them. The Taliban insurgency across the border in Afghanistan was not expected to be affected.