【明報專訊】US PRESIDENT Donald Trump having announced he has cancelled the US-North Korean (NK) summit scheduled for next month, the Korean Peninsula crisis has renewed. How things will develop hinges on whether the two sides can refrain from further irritating each other. The key reason why the US-NK summit plan has fallen through is surely the fact that the US adheres to its tough position that NK should unilaterally abandon its nuclear efforts first. China did try hard to mediate between NK and the US, but it eventually failed to save it. Trump, who had agreed to meet Kim Jong-un, but suddenly cancelled the meeting yesterday, gives people the impression that he tends to trifle with serious matters and has no comprehensive strategies. US-NK relations are at a critical historic juncture. However, because he concerns himself only with how to get all the advantages at the conference table, Trump has ruined an opportunity to bring peace to the peninsula. One who wields such great power in the world acts in such a self-willed manner. Trump has become the biggest factor in instability on the face of the globe.