WASHINGTON—President Joe Biden plans to nominate Rahm Emanuel, who previously served as chief of staff to former President Barack Obama and mayor of Chicago, as U.S. ambassador to Japan, the White House said on Friday. White House officials lauded Emanuel’s experience and long years of public service. His nomination was announced on the same day that the White House disclosed that veteran U.S. diplomat Nicholas Burns was picked to serve as U.S. ambassador to China. Emanuel said he was honored to be tapped for the job. “The alliance between the United States and Japan is the cornerstone of peace and prosperity in a free and open Indo-Pacific,” Emanuel said in a statement. House Speaker Rep. Nancy Pelosi (D-Calif.) welcomed the announcement, saying Emanuel’s “relentlessness and track record of success” would help him as he works to deepen one of the most important U.S. alliances and advance regional security. The White …