US officials say military buildup in China related to N. Korea tensions, tanks spotted China continued moving tanks and armored vehicles and flying flights near North Korea this week as part of a military buildup in the northeastern part of the country that U.S. officials say is related to the crisis with North Korea. The Obama administration, meanwhile, sought to play down the Chinese military buildup along the border with Beijing's fraternal communist ally despite the growing danger of conflict following unprecedented threats by Pyongyang to attack the United States and South Korea with nuclear weapons. According to U.S. officials with access to intelligence reports, both intelligence and Internet reports from the region over the past week revealed the modest military movements in the border region that began in mid-March and are continuing. The buildup appears linked to North Korea's March 30 announcement that it is in a "state of war" with South Korea after the United Nations imposed a new round of sanctions following the North's Feb. 12 nuclear test and because of ongoing large-scale joint U.S.-South Korea military exercises. The People's Liberation Army (PLA) troop and tank movements were reported in Daqing, located in northeastern Heilongjiang Province, and in the border city of Shenyang, in Liaoning Province. Officials said one key military unit involved in the mobilization is the 190th Mechanized Infantry Brigade based in Benxi, Liaoning Province. The brigade is believed to be the PLA's frontline combat unit that would respond to any regional conflict or refugee flows. Troops and tank movements also were reported in Dandong, in Liaoning Province.