On Jan. 6, China celebrated the first anniversary of its first international naval combat mission. For more than a year, China's rapidly modernizing navy has been escorting merchant ships through pirate-infested waters off the coast of Somalia. Such a mission benefits all by helping to defend international sea lanes.

But Beijing's ultimate goal in modernizing its navy does not appear to be preventing piracy around the world. Instead, as America's senior military officer, Chairman of the Joint Chiefs of Staff, Adm. Michael Mullen, pointed out in May 2009, China appears to be trying to counter the U.S. military in East Asia. A more powerful Chinese navy may hinder the U.S. military's ability to support long-standing security commitments in the region.

China's growing naval capabilities are detailed in the annual report to Congress of the U.S.-China Economic and Security Review Commission, of which we are members (www.uscc.gov). The commission, an official body advising Congress on economic and security issues related to China, concludes that for more than a decade, China has been aggressively modernizing its naval forces. It has launched more than 38 modern submarines and 29 surface ships. It is seeking to develop its first aircraft carrier. China has also expanded and improved its naval weapons, such as advanced antiship and land-attack cruise missiles. Seeking to ensure that these new vessels and weapons operate effectively, China has improved its command and control capabilities.

China also appears to be on the cusp of fielding the world's first antiship ballistic missile, capable of hitting moving ships far out at sea. As of right now, there is no defense against such a capability. In effect, targeted ships would be sitting ducks.

As the commission's report demonstrates, a key goal of China's naval modernization is to inhibit the U.S. military from operating in the western Pacific in the event of a crisis between the two nations. The most likely scenario would be during a conflict between China and the United States over Taiwan, an island nation that China considers a renegade province. Were the Chinese military to threaten democratic Taiwan, the United States would potentially intercede on Taiwan's behalf. It has done so before, most recently in 1996 when the U.S. deployed two carrier battle groups to the region.

An accidental clash between the U.S. and Chinese navies over freedom of navigation in the South China Sea is also possible. For example, Chinese vessels dangerously harassed U.S. surveillance ships in international waters off China's southern coast in early 2009.

In the event of an international incident, the U.S. Navy would encounter some difficulties. Chinese submarines are quieter and deadlier than ever, and their destroyers and frigates highly capable. Their antiship cruise missiles are specifically designed to penetrate U.S. naval defenses. According to the Department of Defense, Chinese land-attack cruise missiles are capable of hitting U.S. military bases in Asia, such as on Okinawa and Guam. Most alarmingly, when fully developed and deployed, their antiship ballistic missiles may be able to hit U.S. aircraft carriers—potentially knocking out the centerpiece of U.S. naval power since World War II.

Currently, the U.S. Navy in East Asia still maintains a strong lead in capabilities over the Chinese navy. However, unless the United States takes certain actions, this gap will shrink in the coming years. Ensuring that the U.S. Navy has adequate resources to counter China's growing submarine capabilities will help. So, too, would finding a way to defend our ships against China's antiship cruise and ballistic missiles.

Most importantly, Beijing needs to be more transparent about the goals of its naval modernization and the intentions for its new and improved navy. A clearer articulation of these goals and intentions would help allay some of these anxieties, prevent unintentional incidents at sea, and enhance the security of both the United States and China.

Jeffrey L. Fiedler and Dennis C. Shea are commissioners with the U.S.-China Economic and Security Review Commission. They wrote this commentary for The Advertiser.