WASHINGTON  As Taliban militants push deeper into Pakistan’s settled areas, foreign operatives of Al Qaeda who had focused on plotting attacks against the West are seizing on the turmoil to sow chaos in Pakistan and strengthen the hand of the militant Islamist groups there, according to American and Pakistani intelligence officials.

One indication came April 19, when a truck parked inside a Qaeda compound in South Waziristan, in Pakistan’s tribal areas, erupted in a fireball when it was struck by a C.I.A. missile. American intelligence officials say that the truck had been loaded with high explosives, apparently to be used as a bomb, and that while its ultimate target remains unclear, the bomb would have been more devastating than the suicide bombing that killed more than 50 people at the Marriott Hotel in Islamabad in September.

Al Qaeda’s leaders  a predominantly Arab group of Egyptians, Saudis and Yemenis, as well as other nationalities like Uzbeks  for years have nurtured ties to Pakistani militant groups like the Taliban operating in the mountains of Pakistan. The foreign operatives have historically set their sights on targets loftier than those selected by the local militant groups, aiming for spectacular attacks against the West, but they may see new opportunity in the recent violence.

Intelligence officials say the Taliban advances in Swat and Buner, which are closer to Islamabad than to the tribal areas, have already helped Al Qaeda in its recruiting efforts. The officials say the group’s recruiting campaign is currently aimed at young fighters across the Middle East, North Africa and Central Asia who are less inclined to plan and carry out far-reaching global attacks and who have focused their energies on more immediate targets.