TOKYO — In announcing his decision to exit the Iran nuclear accord, President Trump said he also wanted to send a signal about the kind of hard bargain he plans to drive with another longtime American adversary, North Korea.

Many analysts in Asia greeted the move with skepticism, however, saying it would instead jeopardize the goals of a planned summit meeting between Mr. Trump and North Korea’s leader, Kim Jong-un.

By withdrawing from the Iran deal, analysts said, Mr. Trump has proved the United States to be an untrustworthy negotiating partner that cannot be counted on to honor any agreement.

“Only a fool would trust the US to keep its word in a rogue state nuke deal now,” Robert E. Kelly, a professor of political science at Pusan National University in South Korea, wrote on Twitter.