China's Defense Ministry on Saturday accused the US of committing a "serious military provocation" by flying an Air Force B-52 bomber over a Chinese-controlled man-made island in the South China Sea, and reiterated that it would do whatever necessary to protect Chinese sovereignty.
As is China's usual practice, the Foreign Ministry took a more diplomatic tone. Foreign Minister Wang Yi said that the situation was essentially stable, but that outside nations should not "manufacture tensions."
The Defense Ministry accused the U.S. of deliberately raising tensions in the disputed region, where China has been aggressively asserting its claims to virtually all islands, reefs and their surrounding seas.
"The actions by the U.S. side constitute a serious military provocation and are rendering more complex and even militarizing conditions in the South China Sea," the Defense Ministry said in a statement. It demanded Washington immediately take measures to prevent such incidents and damage to relations between the two nations' militaries.
Why is China's military drawing this line now? Some analysts point out that China's latest protest comes amid a simmering dispute over Washington's approval this past week of the first arms package in four years offered to Taiwan, Beijing's self-governing rival. Beijing, which regards Taiwan as part of its territory, demanded the deal be scrapped to avoid harming relations across the Taiwan Strait and between China and the U.S.
Beijing filed a formal diplomatic complaint and its Foreign Ministry said it would take "necessary measures, including the imposition of sanctions against companies participating in the arms sale to Taiwan."
The main contractor behind the weaponry is Raytheon. U.S. defense firms are forbidden to sell arms to China.
Saturday's statement said Chinese military personnel on the island went on high alert during the Dec. 10 overflight by the B-52 strategic bomber and issued warnings demanding the aircraft leave the area.
"In the face of provocative acts from the U.S. side, the Chinese military will take all necessary means and measures to resolutely safeguard national sovereignty and security and resolutely safeguard regional peace and stability," it said.
Speaking to reporters on a visit to Berlin, Wang drew a contrast between the situation in the region and the chaos and turmoil in other parts of the world.
"The situation in the South China Sea is essentially stable overall," he said.
While China understands the concerns of nations from outside the region — a clear reference to the U.S. — Wang said they should "do more to benefit peace and stability and support efforts to find a resolution through talks, and not manufacture tensions or even fan the flames."
"We don't think this is a constructive approach and will not receive the support and welcome of relevant nations," Wang said.
The U.S. takes no official stance on sovereignty claims in the strategically crucial South China Sea, through which $5 trillion in international trade passes each year. However, Washington insists on freedom of navigation and maintains that China's seven newly created islands do not enjoy traditional rights, including a 12-nautical-mile (22-kilometer) territorial limit.
There was no immediate Pentagon response to the latest Chinese protest. News reports quoted spokesman Cmdr. Bill Urban as saying in Washington that China had raised its complaints over the flight and that the U.S. was investigating.
Urban said the flight was not a "freedom of navigation" operation, indicating that the plane may have strayed off course. The U.S. uses pre-planned freedom of navigation operations to assert its rights to "innocent passage" in other country's territorial waters.
Critics in the U.S. say freedom of navigation operations around the man-made islands appear to contradict Washington's assertions that they have no right to territorial waters in the first place.
As The Christian Science Monitor reported, this is not the first time the US and China have clashed over airspace rights. In November 2013, China declared that all aircraft entering a maritime area between China, Taiwan, South Korea and Japan must notify Chinese authorities beforehand and that it would take unspecified defensive measures against those that don't comply. Neighboring countries and the U.S. have said they will not honor the new zone — believed aimed at claiming disputed territory — and have said it unnecessarily raises tensions.
After the warning, Washington advised U.S. airlines to comply with China's demand that it be told of any flights passing through its new maritime air defense zone over the East China Sea, an area where Beijing said it launched two fighter planes to investigate a dozen American and Japanese reconnaissance and military flights.
Associated Press writer Frank Jordans in Berlin contributed to this report.