China announced its new international ambitions with fireworks and a brass band this month. Last weekend it made a successful unmanned landing on the moon. And its loudly aggressive actions claiming authority over international waters of the South China Sea have rightly alarmed its neighbors and nearly led to a dangerous naval clash with the United States.

On Dec. 14, China joined the United States and the former Soviet Union as one of only three nations to have successfully landed spacecraft on the moon.

China is now the only nation with an active program of lunar exploration. The last United States landing, with a crew of astronauts, was Apollo Mission 15 on Dec. 7, 1972. The last robotic landing was by the Soviet Luna Mission 24 on Aug. 14, 1976.

The Chinese Chang'e-3 spacecraft not only made a successful landing in the Mare Imbrium region of the moon, it also launched an SUV-sized lunar rover named Yutu, or "Jade Rabbit," and sent it scurrying off on a three-month voyage of discovery on the moon surface, powered by its own array of solar panels.

By any measure it's a very significant technological achievement.

Back on earth, however, China's confrontational efforts to assert control over the South China Sea have raised hackles and military risks in Asia. The Pentagon alleged this week that on Dec. 5 a Chinese naval escort deliberately cut across the bow of the U.S. Navy cruiser Cowpens in international waters off the coast of China, causing the U.S. ship to take evasive action. The U.S. immediately complained to China, which answered Monday by claiming that the U.S. ship had harassed and taken aggressive actions toward a Chinese naval exercise involving China's only vertical and short takeoff-and landing (VSTOL) aircraft carrier, the Liaoning, recently purchased from the Ukraine. The Cowpens, it claimed, had approached within 30 miles of its carrier task force.

Ships often pass fairly close to each other in international waters, and the Cowpens was evidently legitimately observing the Chinese naval exercise when challenged by one of its vessels in violation of the international rules of navigation. The Chinese claim against the Cowpens assumes that the Chinese navy, in peacetime, is entitled to completely control the area where the confrontation took place.

China's aggressive action in the Cowpens incident comes on the heels of its recent action demanding that all aircraft crossing a sector of the South China Sea must file flight plans and follow orders from the Chinese air force.

Last Sunday, the Association of Southeast Asian Nations (ASEAN) issued a statement indirectly rebuking China's grab for authority over international air space. It called for "cooperation in ensuring the freedom of overflight and civil aviation safety, in accordance with the universally recognized principles of international law."

On Monday, Secretary of State John Kerry, who was in Vietnam to inaugurate a program of aid to the Vietnamese Coast Guard, was more blunt.

He said the new air defense identification zone raises the risk of "miscalculation" and added, "The zone should not be implemented and China should refrain from taking similar unilateral actions elsewhere, particularly in the South China Sea."

But it will take more than words to check China's growing - and dangerous- military ambitions.