A report by the Washington Post claims China is equipping all of its government and military PCs with a version of the Kylin operating system to make hacking attempts by foreign intelligence services more difficult. The information about the highly secure operating system was made public during a US China Economic and Security Review Commission hearing in late April. In addition to the secure operating system, the computers will also contain a special microprocessor to prevent attacks.
This security-focused and hardened Kylin is based on FreeBSD:
The Kylin (Chinese page link) operating system was developed by China’s University of Science and Technology for National Defence, and although it appears the system is claimed to be proprietary, an analysis of the code(Chinese page link) in the kernel indicates that it is in fact a hardened version of FreeBSD 5.3.
Source: H Online