It is important for nationals securities to have 'full access' to 'code' in operating systems.

Why?

So that we can scrutinize what operating systems do -- no hidden agenda, hidden messengers or trojans or backdoors. Propriety operating systems have undocumented features that one day can be used secretly to shutdown systems, deliver messages/files or allow logins by unintended users...

Opensource operating systems can form the basis for defense -- by configurations and encryption -- without being compromised by non-disclosed features or 'propriety code'.

National securities will require 'supercomputers' that is fast enough to detect and react to breaches.

Possible and low-cost development of supercomputers at present is via clustering of Linux-based computers. (IBM supercomputers and the more recent Chinese supercomputers are Linux clusters.)

Opensource systems encourage skills development, innovation and sharing -- uplifting society standards in more ways than money.

I use and support opensource operating systems and software.