If you like SciFi, and you like action, and military, and military SciFi then you must know about Marko Kloos - Frontlines series. Book 4 is a great read, which comes as no supprise. Andrew Grayson is about as real as they come. Once again, Andrew is on the pointy end of the speer, but the enemy has changed, for the moment anyway.
Chains of Command at Amazon
If you haven't read the other three - you probably should.
Terms of Enlistment - book 1 at Amazon
Lines of Departure - book 2 at Amazon
Angles of Attack - book 3 at Amazon