What is the least far-fetched way to defend against nuclear submarines? [closed]

Question

Since the Cold War, nuclear powers have said "don't mess with me" using the Nuclear triad, nuclear warheads on bomber planers, missile silos, and in submarines. Of these, the most important is submarines. Silos and planes could be wiped out in a first-strike attack, but submarines are stealthy.

If the setting is earth of the not-too-distant-future, what would be the most plausible way for a superpower to strike first and prevent their opponent's second strike?

My ideas so far divide into three categories: 1) sabotaging the subs, 2) blocking the missiles, 3) doxxing the subs.

Sabotaging the subs is probably most realistic. The adversary gets a spy/mole inside the nuclear submarine program, and does something to some vital system (which?) to scuttle all the subs simultanæously.

Blocking the missiles is what most budget goes into researching, but no country can currently block a high percentage of incoming missiles. Hundreds of billions have been spent on this, and it's gotten nowhere, so "one day, someone invented a perfect missile defense" feels like poor worldbuilding.

Unveiling the subs using some sort of enhanced Magnetic Anomaly Detector probably isn't that realistic.

Answer 1

Sabotage and "blocking the missiles" should both be entirely realistic.

You say "no country can block a high percentage of incoming missiles" but that's assuming they are playing by the rules and that we know what everyone's top secret programs are up to. For story creation purposes, you could easily say that the U.S. has secretly been weaponizing space for years. (Kinda like in Maximum Overdrive where the crisis was ended by a "Russian weather satellite" that launched its nuclear missiles...) The U.S. starts a nuclear war and shoots down all the return fire with what turns out to be a fully operational "Star Wars" program that actually began back in the Reagan era and has been kept secret ever since.

But I think a broad "intel" answer works the best. Sabotage would be one arm of this, but probably not the only arm, or the most important one.

If the U.S. were going to first strike Russia (or China, or both), they would want to spend however long was necessary to first identify and track every single nuclear asset that could be used in retaliation. I envision this less of a James Bond action and more of just a good old long running intel program "tagging and tracking", but there may well be some sabotage along the way. Wouldn't it be a shame if these missile silo hatches didn't open? And if, one day, every single enemy nuclear sub was attacked at the same time because we've known for months or years exactly where they are at all times? And actually that the enemy's warhead production has been low-key sabotaged for years and really none of them work? (Or they work fine, but the missiles themselves are too low quality to survive the launch process.)

Really I think the key item here is that it's not "and then one day, they decided to go to war". Whatever scheme was used to prevent retaliation was something they had been working on for a long time. Certainly years, maybe decades.

Answer 2

Consider what actually happened during the Cold War. At least as the US hopes it did happen -- at times they under-estimated the Soviets.

• Build nuclear attack submarines with better stealth and sensors than the enemy missile submarines.
• Use intelligence to detect SSBNs making ready for sea, and dispatch SSNs to lurk near their ports.
• As the SSBN cruises, a SSN follows. Of course the owner of the SSBN will try to "de-louse" their SSBN, perhaps with their own SSN or with surface and aerial ASW forces. They might also try to establish "boomer bastions," entire sea areas near their port defended by their ASW forces rather individual protection.
• If the trailing SSN has success, it waits for the attack signal.
• The trailing SSN is supported, but not replaced by means such as a SOSUS net, ASW aircraft, and possibly futuristic means (orbital radar/lidar to detect the 'wave hump' of a moving sub, thermographs to detect the reactor heat, optical sensors to detect the bioluminiscence of disturbed microscopic lifeforms).

For the near future, the next big thing might be unmaned underwater vehicles or unmanned surface vehicles to trail an enemy SSBN instead of manned subs. The problem is that they might not be able to neutralize it on short notice. So combine them with a ballistic missile version of SUBROC? Or perhaps the UUV do mount the right kind of warhead, but parking a robotic torpedo next to a SSBN in times of crisis could be highly escalatory.

Answer 3

Some good answers here - but I'm going to give a different answers:

Nuclear Submarines are pretty big and there are a very limited number of ports that can service them.

In a fictional setting, one could devise a two-part weapons system:

The first is relatively small, made to look organic (like a rock or similar) and designed to latch onto the Sea Bed. This autonomously fires a very small 'dart' that has a means to attach to a submarine (first thought is magnetic, but IIRC modern subs use Titanium hulls?) and this Dart has a small transmitter that 'blips' at random intervals (Although it uses an algorithm, it uses a combination of water pressure, temperature and speed as the initial bit of randomness).

This Blip might only be done once a day and look like some form of noise to the onboard sensors of the sub, but it's enough for the adversary to know approximately where the Submarines will be (SSBNs when on station on travel at around 5 knots or a brisk walking pace).

The second part of the weapons system is a device attached to Sea/Air assets that transmits a particular signal, when the 'dart' receives this signal, it starts going mental - making all sorts of very easily lock-on-able noise - which leads to the Adversary to be able to initiate a first-strike on all the on-station SSBNs.

This could be co-ordinated with an attack on the Sub Pens/docking facilities to deal with all the ones that are not on patrol.

Answer 4

probably isn't that realistic.

No?

Magnetic anomaly (and other kinds of sensor) have limited range, and need to be put in places where they're not going to be moved by human or natural influences, need to be hard to spot, and need to be accessible so that the data they're collecting can be returned to base.

The solution would appear to be mass production of sensor drones. They could remain silent and undetected for extended periods of time, spread over a huge expanse of ocean, surfacing only to transmit sensor data, either on a prearranged schedule or in an emergency. With much more signal information available, and much more capable data analytics, it becomes increasingly hard to hide your submarines, and there's no real way to know if you've been spotted until the depth charges start falling.

There are countermeasures to the sensor drone network, of course, but they don't look very much like conventional submarines so they are drifting out of the scope of your question.

Answer 5

Just an additional idea for the sabotage route: Maybe your nuclear power inserted a computer virus into the targeting system of the missiles? This would take a lot of preparation and time until all missiles are affected (since they are essentially air gapped and only get updated during maintenance).

For inspiration, you might want to look up Stuxnet. This was a real virus that damaged air gapped equipment used to enrich uranium in Iran.

Also, they might have invented technology to track the submarines. There are already microphones installed on the see floor at strategic places to try and discover submarines nearby - maybe they had a breakthrough on how to track efficiently. A missile is far easier to stop when you know exactly from where it is launched.

Answer 6

The major challenge with intercepting missiles launched from a submarine is that if they can get relatively close to your coastline before they launch, then it can take only a few minutes for the missile to for the missile go from the submarine all the way to the target.

That is a very short amount of time for the military to make a decision regarding what to do. Within a few minutes they need to...

• Determine that this actually is a missile and not something else.
• Get approval from whoever is supposed to authorize a response.
• Press all the right buttons to arm and fire the anti-missile system.
• The missiles need to actually intercept the target. Hopefully far away.

Regarding anti-missile systems, the country of Israel currently has a system called the "Arrow" that can shoot down ICBMs.

Arrow system has been in operation for decades with many successful tests. They claim 90% accuracy with one interceptor (so 99.9% when launching 3 interceptors).

One copy of the system consists of mobile launcher trucks and a radar truck. The system is mobile and can be mass produced. To deploy it you just need to set up a parking lot for the trucks to sit at and some housing for the guys running the trucks.

To protect the coastline from submarines, one would place a set of trucks at least every 50 miles or so. Given the range of the trucks you would then have overlapped defense in case one truck fails. Because your missile batteries are spaced so close together the submarine would have to get within 10s of miles from your coastline before you could no longer intercept the target.

This brings up an important point. You need to make sure you zone out the subs to a good standoff distance. The way to do that is have lots of underwater tracking assets. This would probably consist of some larger fixed sonar facilities, satellite imaging, and swarms (potentially thousands) of underwater drones and mines.

Answer 7

There is a flaw in the premise:

Silos and planes could be wiped out in a first-strike attack, but submarines are stealthy.

Strike doesn't mean hit, strike means positive launch detection. There is no undo button once the missile is launched, short of shooting it down yourself. That means the moment the first missile launches, your country started a global thermonuclear war.

There is enough time between the first launch and the first hit that your enemy could retaliate with their silos and planes on top of all their subs. And it would be unreasonable to assume they wouldn't be ready for it either. If nuclear war has to happen, it won't be from a peaceful DEFCON 5 state, it will be from a state of high tension on both sides. You are contemplating the nuclear option after all, there is no reason to believe they aren't too.

The only surefire war to prevent a second strike would be to completely cripple your enemy's nuclear capabilities before you fire your first shot, and its other ballistic capabilities for good measure too (because retaliating with lots of conventional bombs and missiles is always an option).

But if you can do that somehow, firing nukes would not have any tangible benefit.

Answer 8

Blocking the missiles is what most budget goes into researching, but no country can currently block a high percentage of incoming missiles. Hundreds of billions have been spent on this, and it's gotten nowhere, so "one day, someone invented a perfect missile defense" feels like poor worldbuilding.

This is not as true as you might think - research into anti-ballistic missile tech is relatively limited, because it signals nuclear escalation just as much as missile development does.

During the Cold War, the USA and USSR had a treaty severely limiting anti-ballistic missile armaments (though the article notes that at that point, ABMs could already shoot down submarine-launched missiles, just not the much faster ICBMs). The idea being that claims to a total missile shield would encourage additional nuclear build-up by the adversary to overwhelm it - and would justify that buildup politically, because a superpower with a total shield would have no deterrence from using its nuclear arsenal.

So for your story, just say that the new generation of ABMs (either boost-phase interception or proposed alternatives was more successful than the early, post-treaty attempts at development of these systems.

Answer 9

One expects that the US military already has directional neutrino detectors. The suggestion for a realistic method of constructing a neutrino telescope was made about 1982. It would have required a single crystal of highly isotopically pure material massing about 1 ton, and would have cost a few million dollars. The idea is that neutrinos can scatter off phonon modes in such a crystal with a far larger cross section than capture modes. And can be detected directionally giving the ability to build a telescope. Possibly by putting several in an array you would be able to give 3-D location of any strong neutrino source.

The researcher who was trying to get funding gave a talk at the U of Toronto physics department. In the QA session, it was pointed out this could track nuclear submarines anywhere on the planet. A nuclear reactor is a strong source of neutrinos. The remark was made "So this is more disruptive than Star Wars?" (the then-current suggestion to build a space-based anti-missile defense system). The researcher's response was "If it gets me funding, sure."

As far as is publicly known, he never got funding.