At least not from a warzone, otherwise the Army might track you down.
From: http://www.militarytimes.com/news/2013/02/army-satellite-network-isnt-for-facebook-soldiers-020113/
Soldiers are using a war zone logistics satellite network to surf Facebook, Twitter and other sites that are off limits on Army computers.
And the Army is ordering them to knock it off.
I guess I'm not surprised. We seem to forget that war is an ugly thing, and Facebook/Twitter don't belong on the battlefield. The military's desire to be on social networking is finally crashing into the problem of dwindling resources for communications equipment and usage. Expect more of this as resources continue to be scarce.