"One good spy is worth 10,000 soldiers."
- Sun Tzu, ancient Chinese military strategist

Islamic terrorism is still the greatest threat to our national security, but Chinese espionage against the United States is gaining ground. The FBI says China will be America's greatest counterintelligence problem during the next 10 to 15 years.

China has seven permanent diplomatic missions in the States, staffed with intelligence personnel. But the FBI believes that as many as 3,500 Chinese "front companies" are involved in espionage for the People's Republic of China (PRC) as well.

And with the bureau focused on terrorism, the China challenge is overwhelming the FBI's counterintelligence capabilities.

The PRC has the world's third-largest intelligence apparatus (after the United States and Russia), and it's targeting America's governmental, military and high technology secrets.

China's goal is to replace the U.S. as the preeminent power in the Pacific - even globally. It's using every method possible, including espionage, to improve its political, economic and, especially, military might.

A senior FBI official said recently, "China is trying to develop a military that can compete with the U.S., and they are willing to steal to get it."

One example: Last fall in Wisconsin, a Chinese-American couple was arrested for selling $500,000 worth of computer parts to China for enhancing its missile systems. Even worse: The PRC recently fielded a new cruise missile strikingly similar to the advanced American "Tomahawk."

Chances that the similarities are a coincidence? Slim to none.

Naturally, America's hi-tech centers are a potential gold mine for Chinese spies. The FBI claims that Chinese espionage cases are rising 20 to 30 percent every year in Silicon Valley alone.

But don't think James Bond. It's all much more methodical - and mundane.

Chinese intelligence collection uses numerous low-level spies to painstakingly collect one small piece of information at a time until the intelligence question is answered. Kind of like building a beach one grain of sand at a time.

For instance, it took China 20 years to swipe American nuclear warhead designs from U.S. national nuclear weapons labs, according to a 1999 congressional committee

China also doesn't rely on "professional" spies stationed overseas to the extent other major intel services do. Instead, it uses low-profile civilians to collect information.

The PRC's Ministry of State Security (MSS) often co-opts Chinese travelers, especially businesspeople, scientists and academics, to gather intel or purchase technology while they're in America.

The MSS especially prizes overseas Chinese students, hi-tech workers and researchers living in the U.S. because of their access to sensitive technology and research/development that Beijing can use for civilian and military purposes.

Of course, not all the 150,000 Chinese students and researchers now in America, or the 25,000 official PRC delegates - or the 300,000 victors - are spies, but they do provide the MSS with a large pool of potential recruits for collecting secrets on U.S. targets of interest.

The MSS also recruits in the Chinese-American community, including sleeper agents. Developing personal relationships, invoking a common heritage, threatening alienation or offering access to power are persuasive in a culture where "guanxi" (connections) are important.

An equal opportunity employer, the MSS will, of course, "hire" sympathetic Americans - or any ethnicity - that will further China's cause, including scholars, journalists and diplomats, among others.

The United States isn't the only country with a Chinese spy problem. The MSS runs an espionage network against scientific labs and large research universities in several European countries, including the U.K., France, the Netherlands and Germany. In Asia, Taiwan recently arrested 17 of its military officers for working for the PRC.

China's spies and their methods aren't the most expedient or efficient in spy-dom, but the tenacity and quantity of Chinese spooks are proving effective. Unfortunately, the openness of American society provides easy access to sensitive information and technology.

Sun Tzu said that intelligence is critical to success on the battlefield. It applies to the political and economic "battlefield," too. Accordingly, China is investing heavily in espionage to match its geopolitical aspirations.

China will prove to be America's greatest foreign-policy challenge in this century. In recent months, the Pentagon, CIA, Treasury and Congress have voiced concerns about China's rapidly expanding political, economic and military clout. These are words to the wise.

We certainly can't take our eye off terrorist threats against the homeland, but neither can we risk not meeting the growing Chinese espionage menace. Both are major threats to our national security and merit significant resources and attention.

Peter Brookes is a Heritage Foundation senior fellow.