U.S. President Donald Trump and First Lady Melania Trump sent their "profound congratulations" Tuesday to Japan's Emperor Naruhito and Empress Masako, after the emperor's ascension to the throne.

"We will renew the strong bonds of friendship between our two countries," Trump said in a statement, referring to Japan's new imperial era of Reiwa, which the enthronement ushered in.

"'Reiwa' means 'beautiful harmony,' and it is our sincere wish that our alliance continue to flourish and deepen in this spirit," Trump said.

The Trumps are set to be the first state guests welcomed by Emperor Naruhito, when they visit Japan on May 25-28.