US President Barack Obama has named senior diplomat Daniel Russel as assistant secretary of state for East Asian and Pacific Affairs, the White House said on Wednesday.

Russel, formerly senior director for Asian affairs at the White House's National Security Council, fills the post left vacant on Feb 8 by Kurt Campbell, who is now chairman and CEO of The Asia Group, a strategic advisory and investment firm he founded after leaving office.

Russel's appointment comes as the US administration faces a series of challenging issues, including denuclearization on the Korean Peninsula. The Democratic People's Republic of Korea conducted its third nuclear test in February.

Expert on Japan

China and the Republic of Korea are both at odds with Japan over territorial disputes and historical issues left over from World War II. Meanwhile, China and the US are exploring "a new type of major power relationship" as proposed by President Xi Jinping.

Russel joined the US Foreign Service in 1985. He also served as National Security Council director for Japan, the ROK and DPRK from 2009 to 2011. He was formerly head of the State Department Office of Japanese Affairs and worked at consulates in Osaka and Kobe, Japan, and the US embassy in Seoul. Russel is widely regarded as an expert on Japan, but he also has extensive knowledge of the Korean Peninsula and East Asia.

Orville Schell, director of the Center on US-China Relations at the Asia Society, described Russel as a very knowledgeable, experienced and able Asia specialist with important diplomatic skills that have been sharpened in the National Security Council.

"My main concern is that the Obama administration currently lacks a high official with strong China experience and a record of dealing face to face with Chinese officials," he said.

"I hope the Obama administration will find a way to remedy this gap, possibly even by designating someone like Vice-President (Joe) Biden, as president Bush designated Hank Paulson, to carry a special interdepartmental 'China portfolio'" Schell said.

China-US relations have the best prospects of stability when there has been someone on each side to serve as an effective, high-level go-between, he said.