Two unarmed U.S. Air Force B-52 bombers entered a Chinese air defense zone on Monday, defying China’s expanding claim over an island chain in the East China Sea.

The flight occurred without incident, and the Pentagon declared on Tuesday that the flyover was not significant of any reaction to China’s expanding declaration of sovereignty over the archipelago which that country calls the Diaoyu Islands. Japan calls the group the Senkaku Islands, and both nations claim dominion over the region, as well as over the oil and gas fields nearby.

The B-52 flyover comes directly after U.S. Defense Secretary Chuck Hagel’s scathing comments rejecting Chinese air defense zone expansion in the area, which some see as a threat to regional stability. Hagel said over the weekend, “We view this development as a destabilizing attempt to alter the status quo in the region. This unilateral action increases the risk of misunderstanding and miscalculations.” Both China and Japan have been harassing one another over the island chain for years.

The two B-52 Stratofortresses departed from Anderson Air Force Base in Guam, and China issued an initial public response on Wednesday, stating that the planes were detected and monitored as they flew over the zone, for two hours and 22 minutes. Beijing asserted its right to monitor aircraft entering the region, but did not include any threats of taking action against any offending planes.

Lieutenant Colonel Tom Crosson, a U.S. Department of Defense spokesman, commented that the two unarmed, long-range strategic bombers flew “as part of a long-planned training sortie,” adding that the Chinese did not attempt to challenge the flight whatsoever. Crosson also pointed out that the US pilots didn’t announce themselves to any Chinese authorities.

China is scheduled to participate in the major Rim of the Pacific wargame alongside the US navy and its regional allies next year, which is intended to forge stronger U.S.-Chinese military ties.

Nick Szechenyi, of the Center for Strategic and International Studies, commented on the flyover, “Engagement with China is very important to assure China its rise is welcome, but on the flip side, you have to dissuade China from taking potentially destabilizing actions.”

Image via Wikimedia Commons.