Ise-Shima, Japan - US President Barack Obama on Thursday criticised presumptive Republican presidential nominee Donald Trump's policy ideas as demonstrating "ignorance" of how the world works.
Trump, the billionaire US real-estate mogul and reality TV star, 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 US border with Mexico to keep out illegal immigrants and vows that he will get the southern neighbour to pay for it.
"A lot of the proposals that he has made demonstrate either ignorance of world affairs or a cavalier attitude or an interest in getting tweets and headlines," Obama told reporters on the sidelines of the Group of Seven summit.
"They are paying very close attention to this election," Obama said, referring to other world leaders.
"I think it's fair to say they are surprised by the Republican nominee," he added.
"They are not sure how seriously to take some of his pronouncements. But they're rattled by them, and for good reason." 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 US city of San Bernardino.
He has disdained the usual cautiousness of past candidates for the country's highest office - Republican or Democrat - who while appealing to their base constituencies have still often tried to take positions closer to the centre that would appeal to broad cross sections of the electorate.
November's election to succeed Obama, who is wrapping up a second term, is shaping up to be the nastiest campaign in recent memory as voters express historically deep and practically identical levels of discomfort with both Trump and chief rival, Democrat Hillary Clinton.