Trump in Japan: US president meets Emperor Naruhito

US President Donald Trump has become the first foreign leader to meet Japan's Emperor Naruhito.

Mr Trump, who is currently on a four-day state visit to Japan, was greeted by the emperor and Empress Masako at the Imperial Palace in Tokyo.

The US leader said ahead of the meeting that it was a "great honour".

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.

The US president is said to have given a slight bow to the emperor and empress before entering the palace, according to news wire Reuters.

Mr Trump and Mrs Trump will return to the Imperial Palace later in the evening for a dinner banquet.

Mr Trump met Emperor Naruhito at the Imperial Palace in Tokyo

Mr Trump reviewed the honour guard during a welcome ceremony

'Human defect'

Mr Trump and Japanese Prime Minister Shinzo Abe met on Monday at the Akasaka Palace - a state guest house - where they discussed trade and relations with North Korea.

Ties with the US are of great strategic importance to Japan, and the countries are currently working on a bilateral trade agreement.

Mr Trump had earlier met with the families of Japanese citizens who were abducted by North Korea decades ago, to train North Korean spies in Japanese language and customs.

The decades-old issue is a painful chapter in relations between Pyongyang and Tokyo.

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North Korea has admitted kidnapping 13 Japanese citizens in the 1970s and 80s, and returned five to Japan in 2002. It maintains the rest are dead - something Japan does not believe.

Mr Abe said at a press conference following the meeting that the abduction issue remained the "most important thing" for his government, adding that the families were "appreciative" of Mr Trump's visit.

"Irrespective of my term in office I have to do everything I can for the resolution of this issue," he said.

Mr Trump also spoke about relations with North Korea, reiterating that the country had "tremendous economic potential".

He called its leader Kim Jong-un a "smart man" and said he was "very happy" with the way North Korea was going.

His remarks come hours after North Korea called US National Security Advisor John Bolton a "war maniac".

"Such human defect must go away as soon as possible," said a spokesman for the North's ministry.

When asked if he shared Mr Trump's optimism on North Korea, Mr Abe said that the US leader had "cracked open the shell of distrust".

Mr Trump and Mr Abe held talks at the Akasaka Palace on Monday

Mr Trump also spoke about US relations with Iran noting that Mr Abe was close to the leader of Iran.

"I do believe that Iran would like to talk and if they'd like to talk, we'd like to talk also," newswire AFP reported him as saying. "Nobody wants to see terrible things happen, especially me."

Mr Trump recently announced that the US would be sending 1,500 troops to the Middle East as tensions rise between the US and Iran.

He appeared to express support for Mr Abe to help facilitate talks with Iran, amid local media reports the Japanese leader is considering a trip to Iran next month.

Golf buddies

The bilateral meeting comes after the two leaders met on Sunday to play golf and watch a sumo tournament together.

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Mr Abe tweeted a selfie they took at the Mobara Country Club golf course, south of Tokyo.

The pair are regular golf partners, and Mr Trump has noted their "very, very good chemistry".