President Obama has been critical of presumptive Republican presidential nominee Donald Trump in recent weeks and he spent part of his time at the G-7 Summit in Japan to describe the rancorous U.S. presidential race.
"They're rattled by him and for good reason," Obama said.
"Because a lot of the proposals that he's made display either ignorance of world affairs or a cavalier attitude or an interest in getting tweets and headlines instead of actually thinking through what is required to keep America safe."
Trump is steadily piling up the delegates on the way to his eventual nomination, while the Democrats face a fork in the road: unite or continue towards a testy convention.