Russia is building 2 more ballistic-missile subs, the latest in a long line of ‘boomers’ that worry its rivals

• In August, Russia officially marked the start of construction on two new Borei-A-class submarines.
• The class is Russia's newest, most advanced class of nuclear-powered ballistic-missile submarine.
• The five Borei-A-class boats now being built show that Russia's SSBN modernization is moving full speed ahead.

In August, Russia officially marked the beginning of construction on two additional Borei-A-class submarines, with President Vladimir Putin attending their keel-laying ceremony via video.

The boats, Knyaz Potemkin and Dmitry Donskoy, bring the total number of Borei-class nuclear-powered ballistic-missile submarines, designated SSBNs, under construction to five.

The ceremony, which also marked the construction of two diesel-electric submarines and two corvettes, was held some four months after Russia's navy said it would begin decommissioning the Ekaterinburg, one of its seven Delta IV-class SSBNs.

Since its first SSBN was commissioned in 1960, the Soviet Union and now Russia has operated five classes of "boomers," some of them with their own subclasses.

Events this year show that Russia is now moving full speed ahead on its modernization of that SSBN fleet, which has long been feared by its rivals.

First try

The first SSBNs to enter service with the Soviet Navy were those of the Hotel class. Modeled after the November class, the Soviet Union's first nuclear-powered attack submarines, eight Hotel-class boats were built between 1958 and 1962.

Hotel-class SSBNs had blunt bows and forward-set sails. Their only armament was three missiles carried in silos directly behind the sail, similar to the Soviet Navy's earlier diesel-electric ballistic-missile subs.

They were originally armed with R-13 submarine-launched ballistic missiles, which could only be launched when the sub was surfaced. Subsequent upgrades to the launching systems enabled Hotel-class subs to carry R-21 SLBMs, the first Soviet SLBM that could be fired while submerged.

Hotel-class subs were built hurriedly to keep up with the US Navy, which commissioned the world's first nuclear-powered submarine, USS Nautilus, in 1954.

The lead boat, K-19, had a troubled history.

In 1961, while on a mission in the North Atlantic, a leak in a coolant pipe almost caused a complete reactor meltdown. Twenty-two sailors exposed themselves to lethal doses of radiation to fix the leak. Eight died within a week, the other 14 over the next two years. In 1969, K-19 was damaged in a collision with the US submarine USS Gato. It suffered two fires in 1972, the first of which killed 28 sailors.

All Hotels were decommissioned between 1987 and 1991.

Yankee-class

The successor to the Hotel-class was much more capable. Yankee-class subs were of a new design with a contoured hull designed to minimize resistance. Thirty-four were built between 1964 and 1974.

They were armed with six torpedo tubes and 16 silos capable of launching newer R-27 SLBMs. In 1977, one Yankee-class sub, K-140, was converted to a test platform for larger SLBMs. With 12 silos, it was designated "Yankee II."

Yankee-class subs gave the Soviet Union its first reliable platform for nuclear-armed patrols just outside the territorial waters of its NATO rivals.

But the class did face setbacks. In 1986, sea water leaked into a missile silo aboard K-219, mixing with missile fuel and causing an explosion. Four sailors were killed, and the sub was lost as it was towed back to Soviet territory.

Between 1979 and 1994, the missile silos aboard all Yankee-class boats were rendered inoperable in order to comply with various arms-control agreements. Many were converted for different uses, including for intelligence-gathering and as cruise-missile and attack submarines.

By 1995, all Yankee-class boats had been decommissioned.

Deltas and Typhoons

In 1972, the Soviet Navy commissioned its first Delta-class SSBN. With four total subclasses, the Deltas formed the backbone of the Soviet and Russian SSBN fleet for decades.

A total of 43 boats were built: 18 Delta-Is, four Delta-IIs, 14 Delta-IIIs, and seven Delta-IVs. The first 18 boats could only carry 12 SLBMs; the rest could carry 16.

Armed with the R-29 Vysota family of missiles, which have ranges of 4,000 to 5,000 miles and carry multiple independently targetable reentry vehicles (MIRVs), the Deltas had a massive advantage over their predecessors in that they could patrol much farther from NATO countries than previous Soviet SSBNs and still be an effective deterrent. This was particularly true deep in the Arctic.

Soviet SSBN development didn't stop with the Deltas. The final six Soviet SSBNs, all from the Typhoon class, are the largest submarines ever built.

Developed in response to the US Navy's Ohio-class SSBNs, the Typhoons each displace roughly 48,000 tons - the same as some World War II battleships. They were so large that a sauna, swimming pool, and gym could be installed. They were also capable of 120-day deployments.

Armed with 20 R-39 Rif SLBMS with as many as 10 MIRVs each, a single Typhoon can launch as many as 200 nuclear warheads at targets over 5,000 miles away.

Their massive size wasn't just for intimidation. Intended primarily to patrol in the arctic, Typhoons needed to be able to break through thick ice at a moment's notice. Their Delta- and Yankee-class predecessors had to find weaker sections of ice if they needed to surface.

After the Soviet Union dissolved in the 1990s, the Deltas and Typhoons became too expensive to fully maintain, and many were decommissioned.

Only the seven Delta IVs remain in service with the Russian Navy. One of them, Podmoskovye, was converted into a special-mission submarine in 2016 and now conducts intelligence missions. Only one Typhoon boat, Dmitriy Donskoy, is still in service.

Borei-class

The first Borei-class boat, Yury Dolgorukiy, was designed during the Cold War, but its construction didn't begin until 1996, and it wasn't commissioned until 2013.

Each Borei-class boat has six torpedo tubes and 16 silos capable of launching the new RSM-56 Bulava SLBM, which has a range of over 5,000 miles. Each Bulava can carry between six to 10 MIRVs with payloads ranging from 100 to 150 kilotons.

Despite being smaller than the Typhoons, the Boreis are considered the most advanced SSBNs Russia has ever built. They have new electronics and control systems and a pump-jet propulsion system that makes it much quieter than its predecessors.

Because of design changes made during construction delays, there is now a subclass designated Borei-A. These boats are slightly larger and have even more advanced tech.

Four Borei boats are currently in service, with a fifth, Knyaz Oleg, undergoing sea trials, which included test-firing a Bulava SLBM on October 21. The Russian Navy plans to have 10 Boreis in service by the end of the decade.