Kim Jong Un and President Trump (Photos: Reuters, Michael Reynolds/Getty)

President Trump reiterated on Sunday that he believes North Korea and its leader, Kim Jong Un, are misbehaving with their nuclear provocations.

“He’s acting very, very badly,” Trump told reporters aboard Air Force One, following meetings at his golf course and club in West Palm Beach, Fla., late Sunday afternoon.

Trump’s comments come on the heels of a tweet that criticized China for not doing enough to curb North Korea’s nuclear and missile programs.

“North Korea is behaving very badly,” the president wrote on Twitter on Friday. “They have been ‘playing’ the United States for years. China has done little to help!”

Trump’s tweet came as Secretary of State Rex Tillerson was en route to Beijing, part of a high-stakes diplomatic swing through Asia.

At a Friday press conference in Seoul, Tillerson warned that the United States was not ruling out using military force against North Korea.

“Let me be very clear: The policy of strategic patience has ended,” Tillerson said. “We are exploring a new range of diplomatic, security and economic measures. All options are on the table.”

Related: Trump knocks China as Tillerson heads to Beijing

Tillerson was asked about the possibility of preemptive U.S. military action against North Korea.

“Certainly, we do not want for things to get to a military conflict. We are quite clear in that in our communications,” he said. “But obviously, if North Korea takes action that threaten the South Korean forces or our own forces, then that would be met with an appropriate response. If they elevate the threat of their weapons program to a level that we believe requires action, that option is on the table.”

It’s not the first time Trump has talked tough about Pyongyang.

Following a missile threat in January, Trump tweeted: “North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won’t happen!”

Trump, then the president-elect, added: “China has been taking out massive amounts of money & wealth from the U.S. in totally one-sided trade, but won’t help with North Korea. Nice!”

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— Yahoo News Chief Washington Correspondent Olivier Knox contributed reporting.

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