WASHINGTON  The C.I.A. missile strike in Pakistan’s tribal areas on Wednesday may have killed Baitullah Mehsud, the leader of the country’s fearsome Taliban militia, American and Pakistani officials said Thursday.

Officials in Washington and Islamabad were scrambling to make sense of communications intercepts and other intelligence that seemed to indicate that Mr. Mehsud might have been killed in the strike. By Thursday evening, American officials said they were growing increasingly confident that the Taliban leader was dead.

Still, they cautioned that it may be weeks before they are certain, and they may never gain access to the remote location in South Waziristan to perform DNA tests.

“There is reason to believe that reports of his death may be true, but it can’t be confirmed at this time,” said an American official with access to classified intelligence reports.