The Senate voted Wednesday to ratify the New START treaty, which sets new lower limits on the number of nuclear warheads, missiles, submarines and planes in the U.S. and Russian arsenals. The treaty, however, will not come into force for at least a few more months.
What comes next? Here is a guide to the complicated process:
Russian President Dmitri Medvedev has long said he wanted to coordinate Russia's ratification process with the U.S. Senate, so now that it has been approved here the process will move forward there.
It isn't expected to take long for the Duma to approve the pact, but given that the Russian Orthodox Christmas is coming up, the exchange of so-called "instruments of ratification," after which the treaty takes effect, may not happen until later in January.
Each side can inspect the other's weapons. How long does that take?
Once the instruments of ratification are exchanged, that triggers a 60-day period during which both sides prepare for the first inspections of their arsenals. Of course, the U.S. already has already prepared, but this is the "formal" prep period.
After five days, information is exchanged on what types of aircraft will conduct inspections for each side. After 25 days, the list of inspectors and air crew members is provided so they can secure visas. After 30 days, diplomatic clearances are given for aircraft crews and the entry points for inspectors are declared.
After 45 days both sides exchange the first data on the current status and deployment of the intercontinental ballistic missiles, submarine missiles, and long-range bombers that the treaty covers -- for instance.which B-52 bombers are designated for carrying nuclear weapons.
When do inspectors actually return to Russia?
U.S. officials expect inspectors to begin their work very soon, perhaps right at the 60-day mark after the two sides officially exchange ratification notices.
U.S. inspectors had to leave Russia last December when the original START Treaty expired. The Chairman of the Joint Chiefs of Staff, Admiral Mike Mullen, said inspections build trust between the U.S. and Russia, and the longer we go without inspections, the more that trust can be eroded.
Where will they be allowed to conduct inspections? And why does the New START treaty allow for fewer inspections?
Russia has already provided the U.S. with a list of 35 sites subject to inspection under the new treaty -- half of the 70 sites listed under the original treaty. Why the change? Russia says it has closed down many of its nuclear-weapons facilities, and the State Department says the U.S. has independently checked.
Given the smaller number of sites, the New START allows for fewer inspections per year (something Republicans voiced their concern about during the ratification process). Whereas the original treaty allowed for 28 inspections per year per side, the new treaty allows for only 18 per year per side.
What limits does New START set?
The new treaty sets three main limitations for each side:
Reducing each country's nuclear warheads to 1,550.
Limiting the deployment of ICBM launchers, submarine ballistic missile launchers, and heavy bombers to 700.
Limiting the total number those delivery mechanisms to 800, whether deployed or not.
What will happen with modernization of the U.S. nuclear arsenal?
The Obama administration, facing opposition in the Senate from Arizona Republican Jon Kyl, pledged $85 billion over the next ten years to modernize the U.S. nuclear arsenal.
What is next for arms control and other treaties with Russia?
There are a number of steps the U.S. would like to take, though officials would not be pinned down on what is next or when it might come. Here is an abbreviated list:
Tactical nuclear weapons. These shorter-range nuclear weapons were a major Republican concern over the past year and have never been restricted under an arms reduction treaty. Russia is said to have many more than the U.S.
Officials today say both sides will want to take some time, now that New START is approved, to do some homework on tactical nukes before they begin talks on how to reduce those arsenals. But they point out that President Obama has always said, including last year when signing New START, that he would like to engage Russia in negotiations on tactical nukes.
Comprehensive Nuclear Test Ban Treaty. It would ban testing nuclear weapons in all environments. Was adopted by the UN General Assembly in 1996 and signed by the U.S. but failed a Senate ratification vote in 1999. President Obama has said he would like to get a test ban treaty ratified.
Conventional Forces in Europe Treaty. Was negotiated at the end of the Cold War, but Russia suspended participation in 2007 over complaints about U.S. missile defense plans in Europe.