U.S. Says It Will Take Time to Confirm Prigozhin Was Killed in Plane Crash

It may be some time before Western intelligence agencies can say with certainty whether Yevgeny V. Prigozhin, the founder of the Wagner mercenary group, was aboard the plane that crashed in Russia, Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, said on Thursday.

It remained unclear what caused the plane to drop out of the sky on Wednesday, although preliminary U.S. intelligence reports pointed to an internal explosion. Mr. Prigozhin was listed on the plane’s manifest and is…