Donald Trump on Monday became the first foreign leader to meet with Japan's newly enthroned Emperor Naruhito -- an honour Prime Minister Shinzo Abe hopes will help charm the US president when it comes to thorny trade talks.

Emperor Naruhito ascended the throne earlier in May after his father Akihito stepped down - the first abdication by a Japanese emperor in centuries. "It's over 200 years since something like this has happened," Mr Trump said of the abdication on Sunday. "So it's a great honour to be representing the United States."

Mr Trump and First Lady Melania Trump were greeted by a Japanese honour guard and crowds waving US and Japanese flags as part of a formal welcoming ceremony on Monday.

Donald Trump on Monday became the first foreign leader to meet with Japan's newly enthroned Emperor Naruhito -- an honour Prime Minister Shinzo Abe hopes will help charm the US president when it comes to thorny trade talks.

Emperor Naruhito ascended the throne earlier in May after his father Akihito stepped down - the first abdication by a Japanese emperor in centuries. "It's over 200 years since something like this has happened," Mr Trump said of the abdication on Sunday. "So it's a great honour to be representing the United States."

Mr Trump and First Lady Melania Trump were greeted by a Japanese honour guard and crowds waving US and Japanese flags as part of a formal welcoming ceremony on Monday.