Trump cited 57 nuclear weapons in North Korea's arsenal, marking the first time a U.S. official has publicly put an exact number on Pyongyang's stockpile.
Hours after Trump said he expects to hold new talks with Kim Jong Un, South Korea and Japan said several short-range missiles were launched by the North.
The suspected launch on Thursday comes a day after North Korea shrugged off a U.S. decision to scale back military drills with South Korea in an apparent bid to resume diplomacy.