US president Donald Trump has become the first world leader to meet the new emperor of Japan.

The president, who is on a four-day state visit, was the centre of attention at a grand outdoor welcome ceremony at Japan’s Imperial Palace, where he took a solo walk down red carpets and reviewed Japanese troops as the guest of honour.

The pomp and pageantry then gave way to meetings with Japanese prime minister Shinzo Abe about trade and other world issues.

Mr Trump’s “state call” opened with handshakes and greetings from Emperor Naruhito, who ascended to the throne on May 1, and his wife, Empress Masako.

As he approached the emperor, Mr Trump said: “How are you? Thank you very much.” The first lady told the empress: “Nice to meet you.”

After exchanging pleasantries inside the palace, the couples emerged and walked to a raised platform as the national anthems of both countries were played.

Donald Trump and first lady Melania Trump were greeted by Emperor Naruhito and his wife Empress Masako at the Imperial Palace
Mr Trump and first lady Melania Trump were greeted by Emperor Naruhito and his wife Empress Masako at the Imperial Palace (Issei Kato/Pool Photo via AP)

At the White House last week, Mr Trump noted the significance of his meeting with the emperor.

Naruhito took the throne after his father stepped down, the first abdication in Japan’s royal family in about two centuries.

“It’s a very big thing going on with the emperor. It’s something that hasn’t happened in over 200 years,” Mr Trump said. “I am the guest, meaning the United States is the guest.”

“With all the countries of the world, I’m the guest of honour at the biggest event that they’ve had in over 200 years,” he added.

Donald Trump
Mr Trump reviewed Japanese troops as the guest of honour (AP Photo/Evan Vucci)

It is not the emperor who chose Mr Trump as his first state guest.

It was Mr Abe, who is seen by some as using the invitation to meet Naruhito to curry favour with Mr Trump, who is threatening to impose potentially devastating tariffs on Japan’s auto industry, among other tensions in the relationship.

After leaving the Imperial Palace, Mr Trump went to the Akasaka Palace, the Japanese state guest house with lush manicured grounds, for meetings, a working lunch and joint news conference with Mr Abe.

The president also will be the guest of honour at an imperial banquet at the palace hosted by the emperor.