Information released by the White House says the new treaty limits both nations to "significantly fewer strategic arms within seven years" of its signing. One of the limits: 1,550 warheads. "Warheads on deployed ICBMs (Intercontinental ballistic missiles) and deployed SLBMs (submarine-launched ballistic missiles) count toward this limit and each deployed heavy bomber equipped for nuclear armaments counts as one warhead toward this limit," the White House said. There are also limits on launchers.

The treaty lays out a "verification regime" that includes on-site inspections, data exchanges and notifications, the White House said.

"The Treaty does not contain any constraints on testing, development or deployment of current or planned U.S missile defense programs or current or planned United States long-range conventional strike capabilities," the White House said.

Obama said the agreement is part of the U.S effort to "reset" the U.S relationship with Russia.

Negotiators have been working since April 2009 to wrap up the "follow-on" to the 1991 agreement. Talks were difficult, with disagreements over verification, including on-site inspection of missiles that carry nuclear warheads.

The new START would be the first treaty related to arms control since the end of the Cold War, experts have said, setting the stage for further arms reductions that will tackle thorny issues like what to do with non-deployed warheads that are kept in storage, tactical nuclear weapons and further cuts in missiles and launch vehicles.