Only 1500 each

The U.S. and Russia reached a breakthrough agreement Wednesday for a historic treaty to reduce the nuclear arsenals of the former Cold War rivals, the most significant pact in a generation and an important milestone in the decades-long quest to lower the risk of global nuclear war.

After long and trying negotiations, President Barack Obama and Russian President Dmitry Medvedev are to sign the treaty in two weeks in Prague, once final technical details are worked out, officials in Washington and Moscow said. The accord is expected to cut the number of long-range nuclear weapons held by each side to about 1,500, and it raises hopes for further disarmament in the years ahead.

The agreement would still leave each country with a large number of nuclear weapons, both deployed and stockpiled.

Norris, the nuclear weapons expert, and Hans M. Kristensen of the Federation of American Scientists, estimate that the U.S. has 2,150 deployed strategic nuclear weapons and the Russians have about 2,600. The U.S. has another 2,600 warheads held in reserve, plus 500 non-strategic nuclear weapons, by the two experts' estimate. Another 4,200 retired U.S. strategic warheads are awaiting dismantlement.