1 Transfer of Power
2 The Third Option
3 Separation of Power
4 Executive Power
5 Memorial Day
6 Consent to Kill
7 Act of Treason
8 Protect and Defend
9 Extreme Measures
10 Pursuit of Honor
11 American Assassin
12 Kill Shot
13 The Last Man
Some stories absolutely should be read in order. For example, The Third Option ends with the story only halfway resolved. It is finished in the next installment, Separation of Power.
It may seem like a lot of books; but you'll fly through them.
Thank you all. In order of publication it is.