The Black Key. The Hunter series, #2

During military exercises in the Sea of Japan, rogue missiles are launched from a U. S. naval battleship and head directly to the heart of North Korea. During a return trip to Washington, D. C., Air Force Two disappears over the Rocky Mountains. President Jack Meacham was once the former director of the CIA who was instrumental in the collapse of the Soviet regime. Now, nearly three decades later, his past comes back to haunt him with a single message: "Are you willing to sacrifice your life for the good of the whole?"The volley of missiles and the disappearance of Air Force Two were mere flexes of muscle from one man who wielded The Black Key, a tool that is capable of controlling nuclear arsenals and weaponry systems.
It can control and manipulate economies. And it could be the most damning weapon the world has ever seen with a simple push of a button.  Forced to make a choice, the president finds himself at odds with a former operative who seeks to end his life with a single twist of The Black Key. In the 'Most Dangerous Game in the World, ' President Meacham is given two options: "You have forty-eight hours to end your life for the greater good of the whole .