U.S. President Barack Obama said Thursday that global leaders are “rattled” by Donald Trump and have good reason to feel that way, blasting the presumptive Republican presidential nominee for demonstrating ignorance about world affairs.

“They are rattled by it — and for good reason,” Obama said on the sidelines of a Group of Seven advanced economies summit in Japan.

“Because a lot of the proposals he has made display either ignorance of world affairs, or a cavalier attitude, or an interest in getting tweets and headlines,” he said.

Though Obama has generally avoided opining on the presidential race, particularly while the Democratic primary continues to play out, he’s made no secret of his distaste for Trump, a billionaire U.S. real-estate mogul and reality TV star.

Trump’s possible election would mark a sharp departure from Obama in both tone and substance.

Trump has dominated headlines since launching his presidential campaign last year with a mix of incendiary comments and policy stances seen as insulting Mexicans, Muslims and women, among others.

He has proposed building a giant wall along the U.S. border with Mexico to keep out illegal immigrants and vows that he will get the southern neighbor to pay for it.

Trump has also proposed a temporary ban on Muslim immigration, citing fears of jihadist attacks such as those that have occurred in Europe and the U.S. city of San Bernardino.

Obama, taking questions the day before he pays a historic visit to Hiroshima, said foreign countries pay more attention to U.S. elections than Americans do to theirs because they count on the U.S. to provide stability and direction in addressing global challenges.

“I think it’s fair to say they are surprised by the Republican nominee,” Obama said, referring to Trump.