For the first time in 24 years, the U.S. Navy's intelligence branch has published an unclassified report warning against a rapidly rearming and increasingly aggressive Russian fleet.

And while the report—which the Navy intends for public consumption—has been years in the making, recent events have underscored just how serious its findings are. It's becoming clearer by the day that, with the strong backing of President Vladimir Putin, the Russian navy is making a serious effort to challenge the world's preeminent maritime power—the United States.

"Russia has begun, and over the next decade will make large strides in fielding a 21st-century navy capable of a dependable national defense [and] an impressive but limited presence in more distant global areas of interest, manned by a new generation of post-Soviet officers and enlisted personnel," The Russian Navy: A Historic Transition concludes.