Russian President Dmitry Medvedev says a preliminary deal with the U.S. to reduce stockpiled nuclear weapons is a "reasonable compromise" on the crucial issue.

But Medvedev said serious differences remain over the possibility of a U.S. missile shield in Europe.

He spoke at a joint news conference after hours of talks with President Barack Obama.

They struck a preliminary deal to reduce their nations' stockpiles of nuclear warheads to as few as 1,500 each, aiming toward the lowest levels of any U.S.-Russia arms control agreement, and to cut delivery vehicles.

The presidents issued a joint declaration pledging to evaluate ballistic missile threats, but the U.S. did not pledge to refrain from deploying missile-defense facilities in Europe.