The United States and Russia have agreed to cut their nuclear weapons arsenals by about one-third.
US President Barack Obama and his Russian counterpart, Dmitry Medvedev, agreed on the nuclear weapons reduction treaty during a phone call and will sign the deal in the Czech capital, Prague, on 8 April.
The treaty limits both sides to 1,550 warheads, about 30% fewer than are currently allowed, the White House says.
The US is said to have more than 2,000 deployed strategic nuclear weapons, while Russia is believed to have more than 2,500, the BBC reports.
Both sides would have seven years after the treaty's ratification to reduce their long-range nuclear warheads.
The deal replaces the 1991 Strategic Arms Reduction Treaty.