US President Barack Obama's nominee to be his top diplomat to Asia has vowed to work for a "verifiable denuclearisation" of North Korea and help cool tempers over maritime disputes in the South China Sea. Obama's "objective in the region is to create and ensure a stable security environment", Danny Russel told senators on Thursday, adding that "economic openness" was also a main goal. It's essential that we uphold freedom of navigation and commerce Danny Russel Russel, one of the main architects of the Obama administration's rebalance towards Asia, has been tapped to replace Kurt Campbell as assistant secretary of state for East Asia. With nations such as China and India becoming powerful economic engines, the United States has been seeking to head off any possible confrontations over markets and turf, and stamp its influence on the region. Russel told the Senate Foreign Relations Committee that he recognised "the importance of opening markets, of levelling the playing field and deepening America's economic ties to Asia". Turning to two major security concerns in the region, Russel offered assurances that he would work to rein in Pyongyang's suspect nuclear programme and stop South China Seas tensions flaring into conflict. "If confirmed, I would actively pursue the verifiable denuclearisation of the Korean peninsula and work to block North Korea's efforts to proliferate or to blackmail its neighbours," Russel said. Tensions over the North's nuclear programme soared in February after it carried out a third underground atomic blast, angering the international community and triggering tightened UN sanctions supported by Pyongyang's traditional ally, Beijing. Tempers have cooled in recent months, however, amid expectations that Pyongyang may be moving towards dialogue rather than confrontation. China on Wednesday said North Korea has expressed willingness to rejoin long-stalled nuclear talks. Russel, a long-time member of the US Foreign Service who serves as senior director for Asian affairs on the White House National Security Council, said he was deeply concerned about the plight of the North Koreans. "North Korea is choosing not to feed its people. North Korea is prioritising … the pursuit of a useless military capability against an imaginary threat." In the South China Sea, tensions have soared in recent years as Vietnam and the Philippines accuse China of increasingly assertive claims to territories. Russel pledged to try to "do everything in my power to try to lower the temperature, [and] push claimants including China into a diplomatic track". He vowed to warn Beijing that it would only flourish in "a region of law, a region of order and a region of respect for neighbours, not one in which there is space for coercion and bullying". "The United States has a profound interest in the peaceful resolution of territorial disputes in the South and the East China seas. It's essential that we uphold freedom of navigation and commerce," Russel said. Committee chairman Senator Ben Cardin said he anticipated that Russel would be quickly confirmed to take up his new post.