The Caspian has been a strategic backwater with little relevance to the rest of the world for most of its history. But recent discoveries of large oil and natural gas reserves in the sea have set the stage for a regional arms race. Russia, the most powerful player in the Caspian region, has announced a plan to add 16 new ships to its navy. Iran, the second largest naval force in the region, is strengthening its fleet. The country's secretive posture on the sea intimidates its neighbors Azerbaijan, Kazakhstan and Turkmenistan, which are building their own naval forces from scratch with modest assistance from the U.S. Mistrust lingers over the Caspian as each country views the others' naval developments as a security threat and invests heavily in keeping up.