WASHINGTON (Reuters) – U.S. President Donald Trump on Saturday said “only one thing will work” in dealing with North Korea after previous administrations had talked to Pyongyang without results.

“Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid,” Trump said in a tweet. “…Hasn’t worked, agreements violated before the ink was dry, making fools of U.S. negotiators. Sorry, but only one thing will work!”

Trump did not make clear to what he was referring. The president has previously said the United States would destroy North Korea if necessary to protect itself and its allies.