The Pentagon worries about Russia's next stealth submarine

• Expert naval analysis shows that the K-329 Belgorod, which is one of Russia's biggest and most advanced submarines, has started its official sea trials.
• The only submarine larger in displacement than the Belgorod is the Soviet, now Russian, Typhoon class, which also happens to be the biggest submarine ever constructed.
• The K-329 Belgorod may serve as a mothership for a smaller, nuclear-powered submarine, unlike most other types of submarines.
• The Belgorod's two mission profiles seem to be at odds with each other.
• No matter what, the K-329 Belgorod is one of the newest and most advanced submarines in the Russian Navy right now.

Expert naval analysis shows that the K-329 Belgorod, which is one of Russia's biggest and most advanced submarines, has started its official sea trials.

The only submarine larger in displacement than the Belgorod is the Soviet, now Russian, Typhoon class, which also happens to be the biggest submarine ever constructed. The design is also bigger than the largest submarines ever commissioned into the United States Navy, the American Ohio-class submarines. The Oscar-II class submarine, a nuclear-powered cruise missile submarine design, is essentially what the K-329 is.

It's interesting that the Belgorod seems to be able to perform two different but related tasks.

The K-329 Belgorod may serve as a mothership for a smaller, nuclear-powered submarine, unlike most other types of submarines. Because of its ability to dive to great depths, this tiny submarine could carry out a variety of operations on the ocean floor, effectively engaging in deep-sea warfare. 

Even though this is just a theory, the K-329 and its midget submarine payload could be used to cut or splice undersea internet and communication cables, lay mines, and do a number of other covert operations.

The Belgorod's other job, preventing nuclear war, seems to be almost the opposite of what it does in the shadows. Six Poseidon torpedoes in all are mounted on the K-329. But they aren't your typical torpedoes; on top of their conventional, high-explosive anti-ship warhead, they have a nuclear warhead. The Poseidon, however, isn't just one type of torpedo; rather, it's a family of torpedoes that are supposed to have somewhat different properties to better engage a range of targets, from carrier strike groups to coastal communities. They are unlike any other torpedoes that have ever been discovered.

As if the Poseidon's nuclear payload wasn't impressive enough, the torpedoes are also powered by nuclear energy and have a range that is almost infinite. This makes them more like underwater drones than just torpedoes. 

People say that the Poseidon torpedo has a very high top speed, probably over 80 miles per hour and more than twice as fast as most naval surface boats, but it's hard to know for sure.

The Belgorod's two mission profiles seem to be at odds with each other. The Belgorod's clandestine underwater cable manipulation and other missions depend on staying undetected, but launching the largest, fastest, and possibly loudest torpedo in the world (when it's in its final phase) goes directly against staying undetected.

There is still a lot to learn about this new submarine's intriguing origins as well as its distinctive mission profiles. If Russian media sources are to be believed, K-329's base of operations may be in the Pacific Ocean rather than the Atlantic, which could shed light on the project. 

There is still a lot that is clearly unknown. No matter what, the K-329 Belgorod is one of the newest and most advanced submarines in the Russian Navy right now.