Prague, April 8 (Inditop.com/RIA Novosti) Russian President Dmitry Medvedev and US President Barack Obama signed Thursday a new treaty on the reduction of strategic offensive weapons to replace the START 1 treaty, which expired in December 2009.

The document is expected to bring Moscow and Washington to a new level of cooperation in the areas of nuclear disarmament and arms control.

The new strategic arms pact stipulates that the number of nuclear warheads is to be reduced to 1,550 on each side, while the number of operational and stockpiled delivery vehicles must not exceed 800 on each side.

Under the deal, which will have a validity term of ten years unless it is superseded by another strategic arms reduction agreement, strategic offensive weapons are to be based solely on the national territories of Russia and the US.

The document stipulates that each side has the right to unilaterally withdraw from the treaty if it decides that any of the provisions of the treaty could lead to an imminent threat to its national security.

Russia has emphasised its right to withdraw from the treaty if a quantitative and qualitative increase in US strategic missile defence significantly harmed the effectiveness of Russia’s strategic nuclear forces.

The treaty must be ratified by the Russian parliament and the US Congress and will come into force after the sides exchange instruments of ratification.

Russia does not insist on simultaneous ratification of the treaty.

Russian and US senators will hold meetings April 20-21 to discuss the ratification of a new arms reduction treaty.