While there has been an international arms embargo on China since the 1989 Tiananmen Square massacre, this ban did not cover espionage and computer security hardware and software. China has exploited this by importing all the hardware and software they could get access to. Some items were considered illegal for export for national security reasons. But lots of valuable gear is available to sell, although sometimes only to government agencies.
The Chinese have been particularly keen to obtain the latest corporate Internet security and user management software. This stuff has been a key component in the Chinese effort to manage access to the Chinese Internet. This has worked. Foreign intelligence agencies are finding they have an increasingly difficult time getting into Chinese government, and commercial computers. While better use of computer security tools (firewalls, intrusion detection software, etc) has something to do with this, the main reason is the 40,000 Ministry of Public Security employees working for the Golden Shield Project (known unofficially as The Great Firewall of China). The main job of these cops is to monitor Internet use throughout the country, and prevent "troublesome" Internet data from getting in, or out, of China. Since 1998, several billion dollars has been spent on this effort. This has inspired other police states, like North Korea, Turkmenistan, Uzbekistan, Syria, Iran, Cuba, and Myanmar to do the same. All this is not just to control Internet use by locals, but to provide a major tool for protecting state secrets.
While the Great Firewall cannot stop someone expert at how the Internet works, it does greatly restrict the other 99 percent of Internet users. And it provides lots of information about what is going on inside all that Internet traffic. Foreign intelligence agencies are beginning to find the Great Firewall of China is going from "nuisance" to "obstacle." This has put government intelligence organizations in a difficult position. In the U.S., the feds feel compelled to seek assistance from, and work with, hackers who are developing new ways to tunnel through the Golden Shield. There are several non-governmental outfits that are involved with this effort, and most are hostile to intelligence agencies. Nevertheless, some relationships have been formed, to deal with mutual problems.
It's not only the intel agencies who are keen to learn their way around, and through, the Great Firewall. Cyber War organizations see the Great Firewall as a major defensive weapon as well. The Chinese have a much better idea of what is coming into their country via the Internet, and that makes it easier to identify hostile traffic, and deal with it. Some American Cyber War officials are broaching the idea of building something like Golden Shield, just for military purposes. But that would be difficult in most Western countries, because of privacy issues. But with Golden Shield, China could unleash worms and viruses on the Internet, and use their Great Firewall to prevent Chinese systems from becoming infected. China needs every advantage it can get, because it has the worst protected, and most infected, PCs in the world. This is largely the result of so many computers using pirated software, and poorly trained operators. Meanwhile, the thousands of people running the Golden Shield are gaining valuable experience, and becoming some of the most skillful Internet engineers on the planet.