(ExpertInfantry / Flickr)
Since the US developed, tested, and eventually used nukes, nuclear weapons have been the hallmark of a US deterrence strategy that has seen seven decades of relative peace settle over the globe.
Today, the US relies on a the "nuclear triad" for deterrence, which means they can launch nuclear missiles from silos based on land, submarines based in the sea, and bombers flying in the sky.
But that triad is under attack. The argument, mainly emanating from democrats in the House and Senate, is that we should not waste billions on weapons systems we're likely to never use. However, to never have to use these weapons is the best-case scenario, and it is in fact the entire point of the effort.
Each leg of the triad offers it's own unique advantages, and all three of these areas are desperately in need of modernization, even if it costs the US $450 billion.
When a nuclear weapon is modernized, it's the delivery platform that changes, not the warhead itself. The US no longer makes nuclear warheads, and it has been a long trumpeted goal of the Obama administration to move towards disarmament with the distant goal of deterring nuclear attacks on the US or on allies being the sole purpose of the US's nuclear arsenal.
Land based silos scattered across the US provide fixed locations from which the US can mount a nuclear attack. The clear benefit of these bases comes from their situation underground. Even a nuclear attack on one or all of the known sites won't render them useless. They are the fastest way the president can deploy nuclear weapons, and as they are spread out, they would be very hard for an adversary to neutralize all at once. When people talk about the president having "a finger on the button," these are the missiles that button fires.
Currently the silos house Minutemen III intercontinental ballistic missiles that were devised in 1982. These weapons are capable and well-maintained, but they're limited by their aged technology, specifically the targeting system.
(The B-52 with all its ammunition.Tech Sgt. Robert Horstman/US Air Force)
Air-launched nuclear missiles can be fired from bombers or fighters, and provide the most forward-deployable leg of the triad. These air-launched cruise missiles have an incredible range of over 1,000 miles which is hugely important for penetrating contested enemy air spaces. The B-52 can carry 20 such cruise missiles, which can be fired in an overwhelming salvo to neutralize enemy air defenses.
But unlike the ground-based ICBMs, or submarines deep under the sea, the nuclear armed planes provide a showy kind of deterrence. Moving a B-52 to a region, as the US recently has in the Baltics and the Pacific, puts the entire area on notice that the US has laid a powerful chess piece in striking range.