Obviously a sequel, and hard to follow some of the references if you didn't read the prior book, which I didn't.
This book left me a little cold. There was absolutely no character development, so the characters were little more than avatars: The techno-soldier with no leadership experience, The sergeant-major now an advisor to the president, the various other advisors who are the usual predictable political types, etc. There was little evidence that any of these characters had an inner life, a past, or an existence outside of the rather limited dialogue. The characters on the other side are only a little more fleshed out.
There are, on the other hand, long and detailed descriptions of the various military applications - both of thier physical attributes and abilities, and also thier tech geneology. There are also lengthy battle scenes.
The "battle" is largely centered around the illegal immigration and border issues with Mexico, with a seeming goal of pointing out that controlling the border only leads to worse problems on both sides. If you feel strongly about this issue, this may be a book you want to skip.