The comment from UN ambassador Nikki Haley comes as President Trump spoke by phone with Japan's Shinzo Abe.
President Donald Trump spoke to Japanese and Chinese leaders over a possible response to North Korea actions.
The dismal showing for Abe's party is also a stinging rebuke of his 4-1/2-year-old administration.
North Korea has tested several ballistic missiles that landed off Japan's coast this year.
Moon Jae-in has set out his plan to ease tensions on the Korean peninsula.
Japanese leader will discuss Pyongyang’s spat with the U.S. over nuclear tests.
At hate rallies, many have called for Koreans to “get the hell out of Japan” and that foreigners should “all be massacred.”
Japan’s prime minister was the first world leader to meet with Trump after the November election.
The Washington and Florida meetings represent Abe’s latest move to strengthen Japan’s longstanding U.S. alliance in the face of China’s rise.
Trump told a local sports radio station last weekend golf was a better way to get to know someone than lunch and saw his match-up with Abe as a "fun" meeting between partners rather than adversaries.
Abe has reportedly called for officials to gather “tweetable” figures on Japanese companies’ investment plans—and is planning to play a round of golf with Trump.
The Japanese PM’s approval rating fell by 6 percent in a month.
Japanese Prime Minister Shinzo Abe said all four disputed islands belong to Japan.
Some fear talk of revising the post-war constitution will divert attention from economic woes.
President reiterates he won't apologize for decision in 'the midst of war' to drop bomb.
Devastating quake halts factory production; economic damage may exceed $10 billion.
'Race against time' for rescue operations with wind and rain forecast to get heavier on southern Japanese island.