More countries to get new submarines: “They carry a lot of explosive power”

What’s the biggest advantage of a submarine? It can hide underwater, and stay hidden for a very long time.

And submarines carrying missiles with nuclear warheads can, in theory, launch highly destructive weapons from anywhere in the world's oceans.

You can think of them as a mobile launch pad for missiles – capable of moving and hiding underwater.

And they are important to the world's nuclear powers.

“They play a big role. You don't know where they are, and they carry a lot of explosive power,” Steinar Høibråten tells Science Norway.

He is chief scientist at the Norwegian Defence Research Establishment and a specialist in nuclear submarines and nuclear weapons.

“Even if the owner state were to be attacked and destroyed, the submarine would still be there,” he says.

In a hypothetical situation where nuclear war had actually started and missiles with nuclear warheads had been launched at another country, the submarine would remain out there beneath the sea as a kind of insurance.

Deterrence

Nuclear weapons strategists call this deterrence, according to Høibråten.

The submarines are meant to deter an enemy from firing nuclear weapons – because the submarine is a major threat in an unknown location.

From there, it can fire missiles from beneath the ocean surface. The missile breaks out of the water, ignites its rocket engine, and races into the atmosphere at enormous speed. You can see what this looks like in the video below.

The explosive power is tremendous. Several of these strategic submarines carry many missiles with multiple nuclear warheads. We will come back to exactly what this means.

The video shows an American Trident II missile, used by both the United States and the United Kingdom. These weapons can have a range of up to 12,000 kilometres.

That means that the missiles carried by an American or British submarine can reach large parts of the Earth's surface.

And the submarine does this while hiding underwater – for months at a time.

These strategies were developed in the decades following World War II, during the Cold War. But little has changed in how these weapons are used today, Høibråten explains.

Significantly reduced since the 1980s

During the Cold War, the superpowers engaged in a major arms race that made the world a more dangerous place, according to Høibråten.

“The number of nuclear warheads today is less than a fifth of what it was in the 1980s. There are still a lot of them, so it's important to continue disarmament,” he says.

Several decades without refuelling

A nuclear submarine gets its energy from a nuclear reactor. Like a nuclear power plant, the reactor is used to heat water and create old-fashioned steam.

The steam can spin a turbine that either generates electricity or powers the propellers. This has nothing to do with the weapons onboard – a nuclear submarine can be equipped with nuclear weapons, cruise missiles, torpedoes, or drones.

But the advantages of nuclear submarines remain regardless.

These submarines are designed to stay underwater for an incredibly long time without needing new fuel.

An American nuclear submarine can go for 20 years without needing new fuel in its reactor, according to the US Environmental Protection Agency.

In theory, they can remain underwater for extreme periods.

Only limited by the crew

“They have few limitations,” Høibråten says. “The only exception comes from the people on board. It’s difficult to imagine being underwater for many months.”

Submarines can produce both air and drinking water from the surrounding seawater, but food cannot be grown onboard – it has to be replenished in ports.

So it's the people on board that limit what the submarine can do. The American engineer Destin Sandlin documented life aboard a nuclear submarine. The video below makes it clear that food on board is what limits time underwater.

The video also shows that the submarine can carry enough food for at least 90 days. This is an attack submarine, which serves a different role than strategic submarines.

Only six countries in the world have strategic submarines: France, the UK, the US, Russia, China, and India, according to Euronews.

And several of these countries are now renewing their fleets.

Replacing submarines from the 1980s

Strategic submarines cost a lot of money and require an enormous support system to function as intended.

America's new strategic sub, called the Columbia class, costs over 10 billion USD per submarine for the first vessels, according to the US Congress. They are currently under construction and are expected to enter service in the 2030s.

The Columbia class is designed to replace submarines that have been in service since the early 1980s.

The entire programme has a budget of 139.7 billion USD. By comparison, six Norwegian frigates cost around 13 billion USD, according to the Norwegian Broadcasting Corporation NRK (link in Norwegian).

The UK is also in the middle of replacing its older nuclear submarines. These subs are called the Dreadnought class and are expected to enter service in the 2030s, according to the British Parliament.

“They should always be a little better. The ability to remain hidden is very important. If the other side has better technology for tracking them, then you have to build better submarines that are better at hiding,” Høibråten says. “It's a continuous cycle."

Always have to have a nuclear submarine on patrol

Both France and the UK have nuclear strategies based on always having one nuclear submarine out at sea, Høibråten says. Specifically for deterrence.

The British call this Continuous at Sea Deterrent (CASD), according to the Royal Navy.

Høibråten estimates that perhaps between 10 and 20 strategic submarines from the major nuclear powers are active in the world’s oceans at any given time.

There is a lot of secrecy surrounding what these vessels actually do. Yet the Americans, for example, are quite open about what kind of capacity the various missiles and warheads have, according to Høibråten.

“Each submarine may have somewhere between 12 and 16 missiles, and each missile may, for example, have four warheads,” he says.

"A lot of explosive power"

A rough estimate suggests that a single large strategic submarine could target around 50 different sites around the world with the weapons onboard, Høibråten explains.

“They carry a lot of explosive power,” he says.

For example, the nuclear warheads atop the American Trident II missiles are extremely powerful. They can have an explosive power of either 100 or 475 kilotons, according to the Norwegian Defence Research Establishment’s report on nuclear weapons (link in Norwegian).

For comparison, the American bomb dropped on Nagasaki in 1945 had an explosive power of around 21 kilotons.

Is deterrence enough?

In an increasingly unstable world, the question is what should be done with nuclear weapons going forwards.

Internal troubles within the NATO alliance and the relationship with Donald Trump's USA make the future more uncertain, according to Nettavisen, among others.

Does Europe need more submarines with nuclear weapons to be a deterrent?

Høibråten points out that deterrence is primarily a political issue, but also a technical one.

He believes that the current European submarines on continuous patrol, one British and one French, are more than enough to act as a deterrent to a potential adversary.

Høibråten also notes that these submarine weapons are so important that they are likely to remain with us for a long time.

“When disarmament hopefully picks up again, I would expect these to be among the very last systemt to be dismantled,” he says.

The news website Euronews has spoken to Swedish defence expert Hans Liwång, who doesn’t think there is a need for additional nuclear submarines in Europe. He instead says that conventional submarines are more important for some European countries.

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Translated by Nancy Bazilchuk

Read the Norwegian version of this article on forskning.no

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