North Korean leader Kim Jong Un is reportedly in Beijing on Monday for the first time since he became supreme leader in Pyongyang.

US President Donald Trump could be the reason.

Previously, China would not have granted Kim the honor of meeting its president, Xi Jinping.

But after Trump accepted a meeting with Kim, that may have changed.

While Trump's tit-for-tat trading of nuclear threats with North Korea did little to deescalate the situation, his eventual decision to meet with Kim face-to-face likely played in to China's move to meet Kim.

North Korean leader Kim Jong Un is reportedly in Beijing on Monday for the first time since he became supreme leader in Pyongyang, and President Donald Trump could be the reason.

As North Korea's leader, Kim has overseen an extremely rough patch in relations with Beijing.

Kim's aggressive pursuit of North Korea's nuclear weapons program has turned the state into an international pariah and put a magnifying glass on China's involvement with the Kim regime.

At a time when China's President Xi Jinping seeks stability, North Korea's behavior has raised the spectre of war perhaps more than ever. For those reasons, Kim has never met Xi or had a close relationship with China.

"The North Koreans think the Chinese are not showing support, and the Chinese think Kim Jong Un has been defiant," Yun Sun, a North Korea and China expert at the Stimson Center, told Business Insider of the diplomatic falling-out.

Previously, "Xi would not grant Kim the honor, the validation, of having a meeting," Sun said.

But while Trump's tit-for-tat trading of nuclear threats with North Korea did little to deescalate the situation, his eventual decision to meet with Kim face-to-face likely played in to China's move to meet with Kim.

If the Trump and Kim meeting is taking place, "then the only variable has changed" has been Kim getting "acceptance from Trump," said Sun, who said that may have motivated China to change its mind.

"By default, the Chinese leaders’ preference is not to give Kim that kind of recognition," said Sun.

But despite what looks like a diplomatic breakthrough, the meeting between Kim and Xi may not aid the US. China is North Korea's treaty ally, and will likely try to inject its own interests into the negotiations, according to Sun.