How the US Navy's nuclear-powered submarines have quietly dominated the seas for 67 years

• Sixty-seven years ago, the US Navy launched the world's first nuclear-powered submarine, USS Nautilus, which went on to break multiple speed, depth, and travel distance records.
• The US Navy has operated no less than 19 classes of nuclear-powered submarines since Nautilus' introduction — here's how they've evolved over six decades.

January 22 was the 67th anniversary of the launch of the USS Nautilus, the world's first nuclear-powered submarine.

Launched in 1954, Nautilus broke multiple speed, depth, and travel distance records, with a radical new design that marked the arrival of the nuclear age.

Nuclear-powered submarines have a number of advantages over their diesel-electric counterparts.

They can stay submerged at deep depths indefinitely, can sail at maximum speeds for longer, and can operate for years without refueling. (Modern diesel-electric subs running on batteries can be quieter than older nuclear-powered boats, however.)

Moreover, nuclear-powered subs' ability to carry submarine-launched ballistic missiles (SLMBs) make them one of the most threatening weapons in service.

The US Navy has operated no less than 19 classes of nuclear-powered submarines since Nautilus' introduction.

Nuclear-powered attack submarines

Nautilus was designed as an attack submarine, designated SSN.

Displacing 4,092 tons, Nautilus was 323 feet long, 27 feet wide, and armed with six torpedo tubes. It was capable of sailing at over 20 knots on and below the surface and of diving to 700 feet.

Nautilus was the first vessel to reach the geographic North Pole, and the first submarine to make the entire journey submerged - fully opening the Arctic as a theater of warfare for submarines.

Though an attack submarine, it was also an experimental vessel, which was one reason it was the only ship of its class and saw no major action. This was also the case for its successor, USS Seawolf, though Seawolf did tap on Soviet underwater communication lines during Operation Ivy Bells.

Seawolf and Nautilus were followed by 11 classes of SSNs, each with unique features.

The six boats of the Skipjack class were the first with a teardrop hull, which all future submarines had, and the Permit class were the first SSNs armed with nuclear anti-submarine missiles.

The largest SSN classes were the Permit class (14 subs), Sturgeon class (37 subs), and the Los Angeles class (62 subs).

These classes went through extensive modifications and upgrades that enabled them to conduct both anti-ship and anti-submarine warfare missions with dozens of torpedoes and missiles.

Some were also modified to assist in intelligence gathering and special-operations missions, receiving electronic equipment and dry deck shelters for deploying Navy SEALs.

Nuclear ballistic-missile submarines

Seven years after the launch of Nautilus, the US Navy adopted the UGM-27 Polaris SLBM, once again changing submarine warfare and presenting a new nuclear threat to the world.

Nuclear-powered ballistic-missile submarines, designated SSBNs, can launch nuclear missiles while underwater. This, combined with nuclear reactors that allow them to remain submerged almost anywhere on earth for extended periods, make them a massive threat.

The Navy's first missile submarines were five subs built or refitted between 1953 and 1960 that could launch Regulus nuclear-capable cruise missiles from their decks, but they had to surface to do so, and only one, the USS Halibut, was nuclear-powered.

The Regulus subs were seen as a stepping stone to the SSBN, of which the Navy has operated six classes.

The George Washington and Ethan Allen classes had five boats, while the Lafayette class had nine. The James Madison, Benjamin Franklin, and Ohio classes had 10, 12, and 18 respectively.

The first five classes were part of the "41 for Freedom" program, an effort to get at least 41 SSBNs into service as fast as possible. Those vessels were commissioned between 1959 and 1967, each carrying at least 16 missiles.

USS Ethan Allen is the only SSBN to have launched a live nuclear missile, which it did in the Frigate Bird test during Operation Dominic in 1962.

In 1972, the SALT I Treaty limited the number of SLBM launchers to 656. The SALT II Treaty further limited new SSBN capability, and as a result some SSBNs were modified and reclassified as SSNs to allow for the construction of Ohio-class missile submarines.

Ohio class

Ohio-class submarines are the largest in US history. Each displaces 18,750 tons submerged and measures 560 feet long and 42 feet wide. They are also the most heavily armed, with four torpedo tubes and 24 Trident II D-5 SLBMs.

In 2002, the US began converting four Ohio-class boats into cruise missile submarines, designated SSGNs. SSGNs can't carry SLBMs and are instead armed with up to 154 Tomahawk land-attack cruise missiles.

Ohio-class subs can also carry 66 special-operations troops and dry deck shelters to deploy them and SEAL Delivery Vehicles without surfacing. Recent reporting suggests that the SSGNs could be armed with hypersonic weapons as soon as 2025.

Ohio-class subs are currently the only SSBNs in service with the US Navy, making them the entirety of the submarine component of the US's nuclear triad.

Virginia class and Columbia class - the future fleet

The end of the Cold War and declining budgets forced the cancellation of the remaining planned Ohio-class SSBNs and the remaining Seawolf-class SSNs. But the Navy intends to replace them with Columbia-class and Virginia-class subs, respectively.

The Virginia-class attack sub displaces 7,900 tons submerged. It measures 377 feet long, is 34 feet wide, and is armed with four torpedo tubes. It also has 12 vertical launching systems capable of firing Tomahawks or Harpoon anti-ship missiles, allowing it to fill in for Ohio-class SSGNs when they retire.

There are currently 19 Virginia-class boats in service, with nine more under construction and two on order. In addition to a new suite of electronics and weapons, future Virginia-class subs may be fitted with lasers. (The Navy is also looking into sub-launched drones.)

In April 2018, USS John Warner became the first Virginia-class boat to engage in combat when it fired six Tomahawk missiles at Syrian government targets in retaliation for an earlier chemical weapons attack.

Columbia-class subs will have a submerged displacement of 20,815 tons and measure 560 feet long and 43 feet wide. This will make them slightly larger than the Ohio class and thus the largest submarines in US history. Their armament will be 16 Trident II D-5 SLBMs.

The Navy placed a $9.4 billion order for the first two Columbia-class boats in November. All 12 planned Columbia-class boats are expected to be completed by 2042, while at least 46 Virginia-class boats are expected to be completed by 2043.

The Navy submarine force is set to shrink in the coming decades, and there have been delays on the latest version of the Virginia class and on the Columbia class, which now faces tight timelines.

Those challenges have raised doubts about how the service and industry will balance construction of both classes in the years ahead.