President Trump issued a cryptic warning Saturday as speculation mounts over whether he is planning military action against North Korea, saying “only one thing will work” when it comes to the ending the threat posed by the hermit nation.

“Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid hasn’t worked, agreements violated before the ink was dry, makings fools of U.S. negotiators,” he tweeted. “Sorry, but only one thing will work!”