Story highlights Christopher Green: North Korea is not the kind of problem that can be resolved unilaterally, no matter how much Donald Trump might wish it were

That leaves Trump's aggressive rhetoric sounding a little empty, Green says

Christopher Green is a researcher at Universiteit Leiden in the Netherlands and one of the senior editors of Sino-NK, a digital periodical dealing with Northeast Asian affairs. The opinions in this article belong to the author

(CNN) US President Donald Trump has sent Xi Jinping a clear message before the two meet in Florida later this week.

With all his customary bluster, Trump told the Financial Times that China "will either decide to help us with North Korea, or they won't," and if Beijing decides not to, "it won't be good for anyone."

This is standard Trump: an aggressive opening salvo designed to give the US a competitive advantage over Xi Jinping. Faced with a fuzzily-worded ultimatum, the Chinese leader will be on the back foot when the two come face-to-face at Mar-a-Lago.

Certainly, there is a world in which this is a diplomatic masterstroke. In that world, the leader of the US declares that he is ready to take unilateral action against North Korea -- which may include imposing secondary sanctions on Chinese banks and other companies suspected of aiding North Korea.

Accordingly, Xi Jinping concludes that China's main policy goal of ensuring stability along its borders is best served by "helping with" North Korea, which means that Beijing comes down harder on the regime in Pyongyang than it has ever done before.

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