US President Donald Trump has again hinted at military action against North Korea, keeping alive tensions with the isolated nation and distancing himself further from his top aides who favour diplomacy. “Only one thing will work” in dealing with nuclear-armed North Korea, the president wrote in a Twitter post without clarification.

“Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid,” he said. It was not clear what money he meant. 

That approach, he wrote in a follow-up post, “hasn’t worked, agreements violated before the ink was dry, makings fools of US negotiators. Sorry, but only one thing will work!” North Korean officials have previously called some of Trump’s comments and tweets declarations of war. It was the second consecutive weekend in which Trump has taken to Twitter with belligerent messages that contradict his top military and diplomatic advisers, who have advocated a more cautious approach. 

Last weekend, Trump wrote as if to his secretary of state, Rex Tillerson, saying that he was “wasting his time” by trying to talk to the government of North Korean dictator Kim Jong-un to find a peaceful solution to what has become a potential nuclear stand-off. 

The president’s postings a week earlier, just a day after Tillerson, in China, said the United States had established direct contacts with North Korea to “probe” its willingness to negotiate, were widely seen as a humiliation of Tillerson, and not the first. 

Tillerson subsequently denied that he has threatened to resign. The dispute between Trump and Tillerson over North Korea, among other issues, has severely strained relations within the Cabinet. North Korea has conducted half a dozen nuclear tests and Kim has threatened US allies like Japan as well as US territory.