China invented fireworks some 1,000 years ago in hopes of scaring away evil spirits. On Monday, it successfully tested a missile-defense system aimed at scaring away the U.S. from defending the island nation of Taiwan.

By shooting down one missile with another, China demonstrated its growing military prowess. But it also telegraphed its anger over last week’s sale of U.S. Patriot interceptor missiles to Taiwan.

Taipei would use the Patriots to blunt any attack by Beijing’s 1,100 missiles poised just across the Taiwan Strait. China has threatened to use force should Taiwan, which has had its own political system for the past six decades, opt for independence.

There’s no chance China’s gambit will deter the U.S. from backing Taiwan’s ability to defend itself. But the test does signal a ratcheting up of tensions between Beijing and Washington, and highlights the continuing paradox of a strategic rivalry between two of the globe’s biggest trading partners.

The U.S. imports about $1 billion a day in Chinese goods to fill the shelves of Walmarts from coast to coast, making it the second-largest U.S. trading partner after Canada. That’s a far different relationship than the U.S. had with the Soviet Union, its last strategic challenger.

China’s test also highlights what some in the military call a "self-licking ice cream cone” — the perpetual pursuit for primacy that keeps missile plants around the world churning out anti-missile interceptors and interceptor-evading missiles.

While China’s official Xinhua News Agency stressed in a terse, three-sentence announcement of the test that the new system "is not targeted at any country,” it plainly was a shot across the U.S. bow for its continuing weapons sales to Taiwan.

Communist-run China split with nationalist-run Taiwan following the civil war in 1949, and it continues to regard the island as a renegade province. While the U.S. recognizes Taiwan and the mainland as part of one China, it continues to arm Taiwan against any threat of reunification by force — a policy regarded by Beijing as provocative interference in an internal Chinese dispute.

Beijing has declared it will take the island back by force should its leaders seek formal independence, and the U.S. has long hinted it would come to Taiwan’s defense if war broke out. The sale of defensive weapons by the U.S. to Taiwan is required under the 1979 Taiwan Relations Act passed by Congress.

Chinese media in recent days have been slamming the $1 billion sale of more than 200 Patriots and warning that it would chill relations with Washington.

Tempers are likely to flare even more in coming weeks as President Obama meets with Beijing’s Tibetan nemesis, the Dalai Lama, and as Taiwan’s President Ma Ying-jeou visits the U.S.

While the Pentagon said it had received no prior notice of China’s missile test, it added that U.S. space-based sensors "detected two geographically separated missile launch events” leading to an "exo-atmospheric collision.”

The event marked the latest outer-space tit-for-tat between the two nations: In 2007, China blasted one of its own weather satellites to smithereens, generating concern its was perfecting a satellite-killing weapon similar to the one last tested by the U.S. in 1985.

In 2008, the U.S. destroyed a disabled spy satellite with a missile fired from a Navy ship, ostensibly to ensure that the satellite’s 1,000-pound tank of toxic hydrazine fuel didn’t harm anyone on the ground.

The Pentagon spends nearly 10 times as much as China’s official annual defense budget of $71 billion, although military experts believe Beijing’s true military spending is substantially higher.

But any commotion generated by the Chinese test is somewhat passe. Ballistic missiles follow a predictable arc through the skies that makes them relatively easy to target. But both China and the U.S. have developed low-flying cruise missiles designed to fly underneath such anti-missile shields.

TIME