U.S. intelligence officials say a Pakistani Taliban leader died in a firefight several weeks ago.
The officials said Friday their evidence is leading them to believe Hakimullah Mehsud has died.
The U.S. announcement of Mehsud's death follows Pakistan's declaration weeks ago about the militant's death.
U.S. officials say they believe Hakimullah Mehsud died during Taliban infighting following the death of former group leader Baitullah Mehsud, who was killed by a U.S. missile strike in August. The two Mehsuds are not related.
Also on Friday, intelligence officials said a top al-Qaida-linked Uzbek militant leader, Tahir Yuldashev, is believed to have been killed in a U.S. missile strike in South Waziristan in late August.
The Taliban have denied the report of Yuldashev's death.
The deaths of both Mehsuds and Yuldashev would be a blow to the Taliban, creating a rush for naming new leaders.
Pakistani intelligence officials say the military is getting ready to launch an offensive against Taliban and al-Qaida militants in the South Waziristan tribal region.
The Pakistani army has blocked all entry and exit routes out of South Waziristan, where officials believe Taliban fighters are based.