Why is the Nuclear Triad needed if nuclear subs can’t be realistically countered?
In: Technology
There’s been some discussion, at least in the US, that it’s not strictly needed for deterrence, and that deterrent requirements can be met solely with submarines. The UK, for example, has submarines as the only component of its nuclear deterrent.
That said, the different legs of the triad each have their own benefits and help reinforce each other.
– Land-based silos are very quick to react, and are able to launch missiles within minutes. Subs take longer.
They also act as “missile sponges”, in that an enemy seeking to minimize the possibility of retaliation is going to try to neutralize the land-based silos first, which can use up a substantial number of the adversary’s warheads, leaving fewer for other still-strategic but less immediately-threatening targets like military bases and political leadership. Since silos are hardened and missiles are not perfectly accurate, an adversary would want to target each land-based silo with multiple warheads of their own to ensure their destruction. Nuclear warheads and missiles aren’t free, so an attacker would need many more warheads than the defender has silos, which increases the costs to the attacker. When both are party to arms control treaties that limit the number of deployed warheads, this puts strong pressure on the would-be attacker’s targeting decisions (“Do I try to neutralize their silos in a quick sneak attack and not have any missiles left for other targets, or do I risk counterattack by not striking the silos and instead attack other targets?”).
Most silos are in remote, sparsely-populated regions so immediate casualties would be low, thus giving the defender the advantage. Once a silo launches, it poses no further threat and there’s no value in targeting it (unlike a sub, which may launch only some missiles, have more in reserves, and would need to flee the launch area since it’s now clearly announced its location). They’re also relatively cheap, as a silo is just a fancy hole in the ground, maintenance is relatively cheap compared to subs, and you generally need less people-per-missile to support the mission. Since they’re located one one’s home country, they’re easy to protect and hard for an adversary to attack.
There’s also other types of land-based missiles, like road- and rail-mobile launchers that can be kept around a base during peacetime for ease of security and maintenance, but deployed to various dispersed positions during times of elevated tensions. These have various advantages and disadvantages compared to fixed silos.
– Air-launched systems (bombs and cruise missiles) are more flexible, since you can maneuver the launching vehicle into a more favorable position prior to launch. Cruise missiles can take long, meandering paths to avoid detection and interception. Aircraft can be moved around and publicly displayed as a show of military force and political power. (See the various posturing with nuclear-capable aircraft by Russians around Alaska, the US around North Korea, etc.) Basing nuclear weapons in allied countries (under the control of the nuclear state) can provide political reassurance to allies about the nuclear state’s commitment to mutual defense.
– Subs are hard to detect and highly mobile. They all but guarantee a viable second-strike capability and thus deter an adversary from thinking they can win by performing a sneak attack. However, their very invisibility makes them difficult to posture with (though there have been examples of US Ohio-class subs making highly visible port calls in allied countries). Maintenance and crew costs are much higher.
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