The United States will replace its interim ambassador to Japan with its deputy representative to Taiwan, diplomatic sources said Thursday, apparently reflecting Washington's efforts to enhance bilateral cooperation to curtail Chinese pressure on the self-ruled island.

Raymond Greene, deputy director of the American Institute in Taiwan, Washington's de facto embassy in lieu of formal diplomatic ties with Taipei, is expected to arrive in Japan as early as next month, the sources said. Joseph Young, currently serving as charge d'affaires ad interim at the U.S. Embassy in Tokyo, will leave office in mid-June.

Greene assumed diplomatic posts in East Asia including consul general in Okinawa before becoming the deputy chief of the AIT in 2018.

The appointment of a person familiar with matters both in Taiwan and Japan is a message to China showing the unity of Japan and the United States, a U.S. government source said.

A senior official of the Japanese Foreign Ministry welcomed the move, saying, "It will enable Japan and the United States to cooperate more smoothly in supporting Taiwan."

The administration of U.S. President Joe Biden has committed to deepening ties with Taiwan after his predecessor Donald Trump's administration enhanced its support to the island to deter China.

The post of U.S. ambassador to Japan has been vacant since the resignation of William Hagerty in July 2019, with Young, who was then deputy chief of mission at the embassy, appointed interim ambassador.

The Biden administration is planning to appoint former Chicago Mayor Rahm Emanuel, who was White House chief of staff for President Barack Obama from 2009 to 2010, as its new envoy to Japan. But the date of his appointment has not been fixed.