WASHINGTON — Two long-range American bombers have conducted what Pentagon officials described Tuesday as a routine training mission through international air space recently claimed by China as its “air defense identification zone.” 
The Chinese government said Saturday that it has the right to identify, monitor and possibly take military action against aircraft that enter the area, which includes sea and islands also claimed by Japan. The claim threatens to escalate an already tense dispute over some of the maritime territory. 
American officials said the pair of B-52s carried out a mission that had been planned long in advance of the Chinese announcement this past weekend, and that the United States military would continue to assert its right to fly through what it regards as international air space. 
Pentagon officials said the two bombers made a round-trip flight from Guam, passing through a zone that covers sea and islands that are the subject of a sovereignty dispute between Japan and China. 
Officials said there had been no Chinese response to the bomber run. 
Within hours of the Chinese announcement this weekend that it had declared what Beijing termed an “East China Sea Air Defense Identification Zone,” Defense Secretary Chuck Hagel issued a statement expressing deep concern over the action. 
“We view this development as a destabilizing attempt to alter the status quo in the region,” Mr. Hagel said. “This unilateral action increases the risk of misunderstanding and miscalculations.” 
Mr. Hagel noted that “this announcement by the People’s Republic of China will not in any way change how the United States conducts military operations in the region.” 
Pentagon officials said the training sortie by the two B-52s could be seen as underscoring that commitment to preserving traditional rules of international air space. 
Mr. Hagel’s statement said the United States had conveyed “concerns to China through diplomatic and military channels, and we are in close consultation with our allies and partners in the region, including Japan.” 
His statement concluded by noting the United States’ “steadfast in our commitments to our allies and partners. The United States reaffirms its longstanding policy that Article V of the U.S.-Japan Mutual Defense Treaty applies to the Senkaku Islands.” 
The move by China appeared to be another step in its efforts to intensify pressure on Japan over the Japanese-controlled islands in the East China Sea that are at the heart of the dispute. 
The declaration, from a Ministry of National Defense spokesman, Col. Yang Yujun, accompanied the ministry’s release of a map, geographic coordinates and rules in Chinese and English that said “China’s armed forces will take defensive emergency measures to respond to aircraft that do not cooperate in identification or refuse to follow orders.” 
“The objective is to defend national sovereignty and territorial and air security, as well as to maintain orderly aviation,” Colonel Yang said in comments issued on the ministry’s website.