The US Senate on Wednesday ratified the new Strategic Arms Reduction Treaty (START) binding the United States and Russia, a big diplomatic and political win for President Barack Obama.
Here are some key details about the 10-year accord.
Nuclear cuts
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The accord restricts former Cold War foes to a maximum of 1,550 deployed warheads each, a cut of about 30 percent from a limit set in 2002, and 800 launchers and bombers -- enough to blow up the world many times over.
For some, that's a feature, not a bug: Key Republican Senator Lamar Alexander stressed the pact "leaves our country with enough nuclear warheads to blow any attacker to kingdom come" when he announced his support on Tuesday.
Inspections
The treaty, which must still be ratified by Russia' parliament, would resume mutual on-the-ground inspections at the core of Republican icon Ronald Reagan's "trust but verify" arms control mantra.
Those inspections have been on hold since the treaty's predecessor lapsed in December 2009, and resuming them was a key goal of the Pentagon, which offered repeated assurances of its unqualified support for the accord.
Better US-Russia ties?
Obama, who has made the treaty a linchpin of his plan to "reset" ties with Moscow, says the accord will help lock in Russia's help in curbing Iran's suspect nuclear ambitions and help the US-led Afghan war effort.
Republicans opposed to the accord said a too-eager Obama was "snookered" by untrustworthy Russian leaders and caved to a country that is "a protector of none and a threat to many," in the words of Republican Senator Jim DeMint.
"Global Zero"? Not even close.
The treaty is only a modest step towards "a world without nuclear weapons" as described by Obama in an April 5, 2009 speech in Prague that helped get him the Nobel Peace Prize despite an absence of concrete achievements.
But that's no surprise for Obama, who stressed in the speech: "I'm not naive. This goal will not be reached quickly -- perhaps not in my lifetime. It will take patience and persistence."
But November 2 elections rout that left Democrats with a badly weakend Senate majority meant START ratification was likely to be Obama's last major gain on nuclear arms control for years.
He has vowed to pursue a treaty to ban nuclear testing, another to end the production of fissile materials for use in atomic weapons, and greater global cooperation on civilian nuclear programs.
Missile defense
Republicans opposed to the pact said it risks handcuffing US plans to deploy a missile defense system that has angered Russia -- a charge flatly and repeatedly rejected by the Pentagon and the White House.
But to soothe some concerns, Obama wrote a letter to lawmakers vowing to field such a shield, and lawmakers were to adopt a non-binding amendment restating Washington's commitments on that front.
They also adopted symbolic amendments committing to keep the US nuclear arsenal up to date, and seeking new talks with Russia on tactical nuclear weapons.
