Here's you a crash course, all the Chicom supercomputers run what is basically a free copy of Linux they got from Red Hat, which they promptly renamed "Red Flag".
http://news.com.com/2100-1014-5253873.html
Several of those countries whose imports are limited, such as China and Russia, have sidestepped the regulations by creating their own supercomputers using clusters of hundreds or thousands of less-powerful systems. The Top500 list of supercomputers, released last week, included five homegrown Chinese computers, including one ranked No. 10.
Another lie. China's most famous supercomputer (Dawning 4000A) does not use Red Flag Linux. It uses a Chinese-customized version of Turbolinux. Yes, Turbolinux, the Japanese company, which has been making lots of money in China. To date, I haven't heard of Red Flag on a supercomputer, as the distro just isn't made for that purpose.
BTW, they teamed with AMD on it, and used proprietary Myrinet interconnect technology. An easy way to hurt foreign clusters is to restrict the sales of the interconnects, as without them it's just a bunch of computers that can't communicate well. The OS isn't anywhere near as important.
I've been waiting, but still no apology or retraction for that blatant lie, only an effort to go on a tangent.
You did know the the "No Such Agency" of the US gov has a security enhanced version of Linux, didn't you? Complete with source code, research papers and methodology. And "anyone" can download it.
I suspect they might even run it on some of their supercomputers.
The horror.