AP Photo

On January 11, a large missile streaked upward from a test site in China. The missile rocketed beyond the atmosphere and struck another similar missile launched from a separate site. Later that day, the official Xinhua news agency announced a "test on ground-based midcourse missile interception technology.'

"The test has achieved the expected objective,' Xinhua proclaimed. "The test is defensive in nature and is not targeted at any country.'

It was a seemingly impressive accomplishment--and apparently a big surprise to Western governments. To date, just one nation has managed to fire one missile to intercept another outside Earth's atmosphere: the United States. And that was after some 20 years of concerted technology development. Today the United States spends around $10...