There isn't really much of a tension there. For the most part liberty increases security; it is only in very narrow situations, such as war-making, that it does not. Several libertarians, conservatives, and even Bruce Schneier have been pointing that out repeatedly, especially in anti-PATRIOT Act articles, over the last decade.

The problem is that many restrictions on freedom can give the illusion of security, and too many people are willing to sacrifice their own and others freedom for those warm fuzzies.