Satan 2, which Putin claimed is already deployed in some missile silos, is a replacement for a 1970s-era Satan ICBM. The new version is slated to reach full service in 50 silos around 2020, according to the Center for Strategic and International Studies.
According to the Center's Missile Defense Project, the Satan 2 "is reported by Russian media as being able to carry 10 large warheads, 16 smaller ones, a combination of warheads and countermeasures, or up to 24 YU-74 hypersonic boost-glide vehicles."
That means one Satan 2 ICBM could pack as much as eight megatons of TNT-equivalent explosive power. That's more than 400 times as strong as either bomb the US dropped on Japan in 1945 — both of which, combined, led to roughly 150,000 casualties.
The technology used to deliver multiple warheads to different targets is called a "multiple independently targetable reentry vehicle," or MIRV. Such devices deploy their warheads after reaching speeds that can exceed 15,000 miles per hour.
Depending on where the warhead is deployed in space and how it maneuvers, each one can strike targets hundreds of miles apart.
Why Putin says the Satan 2 is 'invincible'
A recently demonstrated technology made to neutralize a nuclear warhead is a "kinetic kill vehicle": essentially a large, high-tech bullet launched via missile. The bullets can target a warhead, slam into it mid-flight, and obliterate the weapon.
"But there are a number of different ways to penetrate defenses" like a kill vehicle, Wright said, which may explain Putin's "invincible" claim.
Satan 2 has advanced guidance systems and probably some countermeasures designed to trick anti-missile systems. This might include "a couple dozen very lightweight decoys made to look like the warhead," Wright said, which could result in a kill vehicle targeting the wrong object.
Wright has also studied other methods to sneak past US defenses, including warhead cooling systems that might confuse heat-seeking anti-missile systems, and "disguising a real warhead to make it look different."
But simply deploying large numbers of warheads can be enough: Kill vehicles may not work 50% of the time, based on prior testing, and they're a technology that's been in development for decades.
Yet Satan 2 is not exactly unique.