WASHINGTON — The rise of Imran Khan, a former cricket star who is Pakistan’s likely next leader, could complicate new talks between American diplomats and the Taliban about ending the war in Afghanistan, officials said, fraying an already strained relationship between the nuclear-armed Islamic nation and the Trump administration.

Tensions between Pakistan and the United States were exacerbated in January when the Trump administration suspended nearly all American security aid to Islamabad.

But the relationship threatens to be further inflamed by Mr. Khan, who has voiced past support for the Taliban’s fight in the 17-year conflict in Afghanistan, calling it “justified.” He also has accused the United States of recklessness in its use of drone strikes on suspected extremists in Pakistan, signaling he wants them to stop.

Mr. Khan tempered his harsh anti-American language with an olive twig, if not a branch, in his victory speech last week.