'It has not worked out': Trump tweet hints that the US might take its own action on North Korea

A tweet from President Donald Trump on Tuesday hinted at a change in direction on North Korea policy.

"While I greatly appreciate the efforts of President Xi & China to help with North Korea, it has not worked out," he tweeted. "At least I know China tried!"

The president made the comments a day after an American student, Otto Warmbier, died in the US after being released from North Korean custody.

Otto Warmbier: A timeline of the student's North Korea imprisonment

Trump has repeatedly stressed his relationship with Xi and China as a tool to make progress on reining in North Korea, but has also made clear that the US will seek to unilaterally deal with North Korea should Beijing's efforts fall short.

"If China is not going to solve North Korea, we will. That is all I am telling you," Trump told the Financial Times in April.

China has taken some measures to curb trade with North Korea by rejecting their coal shipments, but they remain the country's main trade partner and engage with it on about 90% of its outside trade. China alone could bring the collapse of Kim Jong Un's regime in North Korea, but it would run contrary to its interests because it would release a flood of refugees and potentially bring forth a democratic, united Korea in which the US could base troops.

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More than presidents before him, Trump has stressed that the US will take on an "all options" approach to dealing with North Korea, and has repeatedly iterated that military action could be in store.

Although experts contacted by Business Insider say that prospects for diplomatic solutions with North Korea look dim, South Korea would resolutely oppose a military engagement.

Along with military action, Trump has also said he would be "honored" to hold talks with Kim Jong Un. White House press secretary Sean Spicer, however, said Tuesday that the Trump administration is moving away from that possibility.

North Korea has multiple times floated the idea of curbing its nuclear weapons program if the US would scale back or stop its military exercises with South Korea. US orthodoxy on the subject maintains that the planned, regularly occurring military drills do not pose a threat to North Korea and do not compare to the Kim regime's regular nuclear threats, but it's possible that Trump could revisit that position.

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