"Only one thing will work" in dealing with North Korea after years of talks with Pyongyang brought no results, US President Donald Trump has warned.
"Presidents and their administrations have been talking to North Korea for 25 years," he tweeted, adding that this "hasn't worked".
Mr Trump did not elaborate further.
The two nations have been engaged in heated rhetoric over North Korea's nuclear activities, with the US pressing for a halt of missile tests.
The president has previously said the United States would "totally destroy" North Korea if necessary to protect itself and its allies from Pyongyang's nuclear threats.
Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid......— Donald J. Trump (@realDonaldTrump) October 7, 2017
Earlier this week, during a meeting with top US military leaders and their spouses, Trump told reporters it was the "calm before the storm." Asked for clarification then on what he meant, Trump said: "You'll find out."
White House spokeswoman Sarah Sanders referred to Iran and North Korea the following day when asked about Trump's comments.
Asked on Saturday about Trump's tweet, the Pentagon said the Defense Department's job was to "present the president military options and carry out orders".
Pyongyang says it has recently successfully tested a miniaturised hydrogen bomb which could be loaded on to a long-range missile.
President Trump has previously warned that the US could destroy North Korea if necessary to protect America's national interests and defend its allies in the region.
- BBC / Reuters