US President Donald Trump said on Saturday that “only one thing will work” to solve the North Korea crisis, although he did not explicitly specify what that would be.

“Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid……” the president tweeted.

“…hasn’t worked, agreements violated before the ink was dry, makings fools of U.S. negotiators. Sorry, but only one thing will work!” he continued in a second tweet.

It’s unclear whether Trump was referring to the nuclear option when he said “only one thing will work.” A senior administration official told Business Insider that the White House had “nothing else to add” to the president’s tweets, and the State Department did not return a request for comment.

North Korea rapidly escalated its nuclear posturing over the summer. The rogue nation fired a missile over Japan a few weeks ago for the second time in two months.

Last weekend, Secretary of State Rex Tillerson told reporters during a visit to China that the US conflict with North Korea is "overheated" and that the first priority was to calm things down. He said that the US has a direct line of communication open with Pyongyang over North Korea's nuclear tests, adding: "We're not in a dark situation, a blackout."

Trump diverged from the US State Department later that weekend and said Tillerson was "wasting his time" opening up talks with the North Korean regime. The president added that being nice to Kim "hasn't worked in 25 years, why would it work now? Clinton failed, Bush failed, and Obama failed. I won't fail."

Trump ramped up his rhetoric against the regime when the United Nations General Assembly convened on September 23, saying that "rocket man" Kim Jong Un was on a "suicide mission," and that if he did not back down, the US would "have no choice but to totally destroy North Korea."

Kim responded by saying he would "surely and definitely tame the mentally deranged US dotard with fire." North Korea's foreign minister, Ri Yong Ho, also said that Trump's comments made the possibility of a missile attack on the US mainland "all the more inevitable."

Ri also said that Trump had "declared a war" on North Korea through tweets he posted after the UN meeting and that the country could shoot down US strategic bombers even if they were not in its airspace, according to Reuters.

Speaking to reporters in New York in September, Ri pointed to one of Trump's tweets that said Ri and Kim Jong Un "won't be around much longer" if the rogue nation continued its nuclear provocations as constituting a declaration of war.

The White House press secretary, Sarah Huckabee Sanders, rejected North Korea's claim later that day."We've not declared war on North Korea," Sanders told reporters during the White House daily briefing. "Frankly, the suggestion of that is absurd."