Fire ice - Clive Cussler (Numa files #3)

Goodreads 3.94

In the heart of the old Soviet Union, a mining tycoon has proclaimed himself czar of Russia. Claiming Romanov ancestry and backed by billions of dollars, he is determined to overthrow the already shaky Russian government-and U.S. opposition doesn't bother him one bit. A little crisis of their own should distract the Americans for a while, and he knows just the thing. . . . 

Filled with all the hair-raising action and endless imagination that are Cussler's hallmarks, Fire Ice is a dazzling thriller from the grandmaster of adventure fiction.