What the US has that compares
The US in 2005 retired the "Peacekeeper" missile, which was its biggest "MIRV-capable" weapon (meaning it could deploy multiple warheads to different locations).
One Peacekeeper missile could shed up to 10 thermonuclear warheads, each of which had a 50% chance of striking within a roughly football-field-size area.
But the US has other MIRV-capable nuclear weapons in its arsenal today.
One is the Trident II ballistic missile, which gets launched from a submarine and can carry up to a dozen nuclear warheads. Another option is the Minuteman III ICBM, which is silo-launched and can carry three warheads.
Arms control treaties have since reduced the numbers of warheads in these weapons — Trident II's carry up to five, Minuteman III's just one — and retired the Peacekeeper.
Today, there are still about 15,000 nuclear weapons deployed, in storage, or awaiting dismantlement, with more than 90% held by the US and Russia.
Cold War 2.0?
Wright said Putin's recent statements and the similarly heated comments and policy made by President Donald Trump echo rhetoric that fueled nuclear arms build-up during the Cold War era.
"What's discouraging is that, at the end of the Cold War, everyone was trying to de-MIRV" — or reduce the numbers of warheads per missile — he said.
Removing warheads helped calm US-Russia tensions and reduce the risk of preemptive nuclear strikes, either intentional or accidental, Wright said. Russia's move to deploy new weapons with multiple warheads, then, is risky and escalatory.
"One of the reasons you might want to MIRV is if you're facing ballistic missile defenses, and Putin talked about that," Wright said, noting that the US has helped build up European anti-missile defenses in recent years. "The clear response is to upgrade your offensive capabilities."
He added that Russia's move also shouldn't be surprising in the context of history: After George W. Bush withdrew the US from the Antiballistic Missile Treaty in 2001, a Russian general told the New York Times the move "will alter the nature of the international strategic balance in freeing the hands of a series of countries to restart an arms buildup."
The charged statements of President Trump, who has called for a new arms race, have done little to reverse that course.
In fact, the Trump Administration plans to expand a Obama-era nuclear weapons modernization program. Over 30 years, the effort could cost US taxpayers more than $1.7 trillion and introduce smaller "tactical" nuclear weapons that experts fear might make the use of nukes common.
This story was published on March 1, 2018, at 5:59 p.m. ET and has been updated with new information.
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