"This is a significant milestone in their effort to develop strategic weapons," said a U.S. official familiar with reports of the test. 
    
U.S. intelligence agencies monitored the flight test of a JL-2 missile about 10 days ago, officials said.
    
The missile was launched from a Chinese submarine near the port of Qingdao and was tracked to a desert impact point in western China several thousand miles away, the officials said.
    
The Air Force's National Air Intelligence Center reported that the JL-2 "will, for the first time, allow Chinese [missile submarines] to target portions of the United States from operating areas located near the Chinese coast."
    
The JL-2 is estimated to have a range of up to 6,000 miles, enough to hit targets in the United States.
    
A defense official said the missile test was a major step forward in China's strategic nuclear missile program and shows an improved capability to produce and launch submarine-launched missiles. "It was a successful test," this official said.
    
The JL-2 is a submarine version of the DF-31 land-based missile.
    
A flight test of the JL-2 last year failed, U.S. intelligence officials said.
    
In December, however, China launched the first of a new class of ballistic missile submarines known as the Type 094.
    
It was not known whether the JL-2 missile was launched from the new submarine or from another submarine modified for missile launch tests.
    
China previously has used a modified Russian-design submarine for missile tests.

The Bush administration has expressed new worries about China's military buildup.
    
Defense Secretary Donald H. Rumsfeld said in Singapore June 4 that China has not disclosed its total military spending.
    
"China appears to be expanding its missile forces, allowing them to reach targets in many areas of the world, not just the Pacific region, while also expanding its missile capabilities within this region," Mr. Rumsfeld said.
    
"China also is improving its ability to project power, and developing advanced systems of military technology," he said. "Since no nation threatens China, one must wonder: Why this growing investment? Why these continuing large and expanding arms purchases? Why these continuing robust deployments?"
    
The Pentagon will highlight the large-scale buildup in its annual report to Congress on the Chinese military, defense officials have said.