US President Donald Trump has said "only one thing will work" with North Korea after past talks with Pyongyang had yielded no results.
"Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid," Trump tweeted on Saturday, Xinhua news agency reported.
"...Hasn't worked, agreements violated before the ink was dry, making fools of US negotiators," Trump wrote. "Sorry, but only one thing will work!"
Trump did not make clear to what he was referring to in his tweets.
White House Press Secretary Sarah Sanders later confirmed to media that all options are still on the table and she had nothing further to add at this time.
Tensions ran high on the Korean Peninsula as North Korea conducted its sixth and most powerful nuclear test on September 3.
In response, the UN Security Council unanimously adopted a new resolution tightening sanctions against Pyongyang. Later, North Korea tested an intermediate-range ballistic missile which flew over Japan.
US Secretary of State Rex Tillerson revealed during a visit to China in late September that the US has direct channels of communication with North Korea.
"We have lines of communications to Pyongyang. We're not in a dark situation or a blackout. We have a couple of direct channels to Pyongyang. We can talk to them ... We've made it clear that we hope to resolve this through talks," Tillerson said.