“At this point, it’s pretty clear world leaders make deals with Trump the way kids do on the playground,” Meyers said of the president on Wednesday.

Leaders from across the European Union held an emergency summit in Brussels to discuss Greenland and, more broadly, their fragile relationship with America.

The president appeared to be lashing out in response to stark, high-profile remarks by Prime Minister Mark Carney of Canada that rejected Mr. Trump’s efforts to dismantle the international order.