U.S. President Donald Trump told his Philippine counterpart that Washington has sent two nuclear submarines to waters off the Korean peninsula, the New York Times said, comments likely to raise questions about his handling of sensitive information.

Trump has said “a major, major conflict” with North Korea is possible because of its nuclear and missile programs and that all options are on the table but that he wants to resolve the crisis diplomatically.

North Korea has vowed to develop a missile mounted with a nuclear warhead that can strike the mainland United States, saying the program is necessary to counter U.S. aggression.

Trump told Philippine President Rodrigo Duterte Washington had “a lot of firepower over there”, according to the New York Times, which quoted a transcript of an April 29 call between the two.