WASHINGTON: President Joe Biden on Friday nominated career diplomat Nicholas Burns as ambassador to China and former Chicago mayor and Democratic party heavyweight Rahm Emanuel to head the embassy in Japan.

The White House also announced Biden had tapped another experienced diplomat, Michael Battle, for ambassador in Tanzania. The ambassador posts require confirmation in the almost evenly divided Senate.

Beijing and Tokyo are in the top drawer of US diplomatic posts, with China an ever-stronger economic competitor, as well as a rising military rival in the Indo-Pacific, while Japan has been a key US ally for more than half a century.

Burns, long a prominent name at the State Department, where he was under secretary of state for political affairs and ambassador to NATO and to Greece, has worked previously with China's government on issues including Afghanistan, UN sanctions on Iran, North Korea and US policy in the Indo-Pacific.

Currently teaching diplomacy and international relations at Harvard's Kennedy School of Government, he has also taught on US-Chinese relations.

The White House said Burns is fluent in French and familiar with Arabic and Greek, but not Chinese.

Emanuel seeks the Japan post with a very different profile.

Before being elected mayor of Chicago, he was best known as White House chief of staff during Barack Obama's presidency.

He also was a Democratic member of the House of Representatives between 2003 and 2009 and served as a political advisor to Bill Clinton during his presidency.

"Rahm Emanuel and Nick Burns are smart decision makers, experienced leaders and dedicated public servants," Clinton tweeted after the nominations were announced.

The Democratic speaker of the House and a close Biden ally, Nancy Pelosi, welcomed Emanuel's nomination, saying "his great experience, from the US House to the White House, will serve our nation well, as he works to deepen one of our nation's most important alliances."