Even as China has taken a great leap forward to acquire a modern deep-water navy, a tone of skepticism has crept into U.S. intelligence and scholarly assessments, some asserting that it will be a decade before the Chinese can seriously challenge the U.S. Navy.

The skeptics are quick to acknowledge, however, that chances of a Chinese miscalculation caused by over-confidence become more possible by the day. Thus they urge the U.S. and China to expand military exchanges and to work out an agreement to prevent an incident at sea from spiraling into a crisis.

The U.S. and the Soviet Union had such an agreement during the Cold War. They agreed, among other things, not to train guns on each other's ships, not to fly over the other navy's ships and to use international signals to avoid collisions.

Reflecting a growing awareness of Chinese naval power is an article by Robert Kaplan, of the Center for a New American Security, a Washington think tank, in the latest issue of Foreign Affairs magazine. "In the twenty-first century," Kaplan said, "China will project hard power abroad primarily through its navy."

Kaplan points to several missions for China's navy, known formally as the People's Liberation Army Navy, or PLAN, as all Chinese military services belong to the PLA. "China's actions abroad," Kaplan said, "are propelled by its need to secure energy, metals, and strategic minerals" to support its surging economy.

The PLAN has been tasked to push China's frontiers into the sea east and south to encompass the self-governing island of Taiwan, Guam and the Northern Marianas that are U.S. territories, the Philippines, and Indonesia. "The Chinese see all these islands," Kaplan said, "as archipelagic extensions of the Chinese landmass."

Further, China is investing in submarines, destroyers, aircraft, and missiles designed, Kaplan wrote, "to block the U.S. Navy from entering the East China Sea and other Chinese Coastal Waters." That "anti-access" or "denial" strategy applies to the Taiwan Strait and the South China Sea, which China claims are territorial waters.

Like other analysts, however, Kaplan acknowledges that China "is still a long way from challenging the United States militarily."

Much attention has been focused on Chinese warships, aircraft, and weapons but the PLAN's greatest weakness is the lack of naval tradition and experience needed to practice good seamanship. American naval officers, chief petty officers and sailors have 400 years of tradition and experience behind them, 200 from the British navy and 200 in the American Navy.

In contrast, China has been a land power that has produced only one great admiral in its long history, Cheng Ho, who led seven voyages into the Pacific and Indian Oceans in the early 15th century. After he died about 1433, China's emperors lost interest in naval exploration and European explorers, merchant ships, and warships began to sail in Asian waters.

Today's PLAN was organized in 1950 after the Communist Party, having defeated Generalissimo Chiang Kai-shek's Kuomintang, had come to power. The PLAN inherited old equipment and poorly trained sailors from the Kuomintang and, in its early days, was trained by the Soviet navy, itself staffed by artillery officers who had been put to sea.

American and Japanese naval officers who have observed PLAN ships maneuver at sea have remarked on the poor quality of ship handling, although one American officer said he had seen improvements. Japanese officers were concerned when a Chinese helicopter flew near Japanese warships south of Okinawa recently, not because it was a threat but because the Chinese pilot wasn't well trained.

Informed analysts said China's military leaders recognized the shortcomings of PLAN sailors and are seeking to train them better.