Unto the Breach (Paladin of Shadows IV) – John Ringo

The fourth book of the series has Mike and the Mountain Tigers has them recovering a WMD from nearby Chechnya.

This is arguably the best in the series. It starts a bit slow, but the last 150 pages or so are one long battle with more excitement and fast moving twists than you can shake a Keldara axe at. At the end, some secrets are revealed. And Mike is broken psychologically. Very nice.