Two missiles fired by the drone killed twelve militants in Pakistan. But authorities are not sure whether Taliban Chief Hakimullah Mehsud perished in the attack.
A Taliban spokesman says Mehsud is safe and had left minutes before the air strike.
Mehsud took over as leader of the Pakistani Taliban five months ago.
His predecessor, Baitullah Mehsud, was killed in a similar U.S. drone strike.
The United States has increased its attacks by its pilotless drone aircraft after a suicide bomber killed seven CIA employees on Dec. 30.