Fortune's Soldier: Shadow Ops Alpha
Sarah Luddington

As a Special Forces Operative he finished his career with an elite British black ops department in Military Intelligence. As tough as it had been, Luke loved his job and his partner, Sam Locke. Sam had once been a US Navy SEAL.
Being a mercenary gives Luke freedom of movement even if he cannot escape his memories.
When their world fell apart, Luke thought he would never see Sam again, until they are recalled to London and sent to Syria. They must transport the one person able to finish tearing them apart. A terrorist who destroyed their lives. Luke and Sam fight to save the world from imminent destruction and fight just as hard for each other.
From the deserts of Syria the men chase a nuclear bomb and weaponised virus through Armenia and into Russia, finding so much more than revenge on the way.
This is a military gay romance with a high death count, torture (not BDSM), and a lot of action.