The United States and Russia were called on Thursday to reduce their nuclear warheads to 1,000 each, as the two began their negotiations on a successor treaty to the expired Strategic Arms Reduction Treaty (START) this week.

International political, military, business and faith leaders participating in the Global Zero initiative summit made the call in a plan released after the three-day meeting in Paris, according to a press release from the initiative's U.S. branch.

The Global Zero called on the United States and Russia "to announce a next round of negotiations to cut their Cold War arsenals to 1,000 total warheads each, including non-deployed and shorter-range tactical nuclear weapons," following the conclusion of the current START replacement talks.

They also called for all other countries with nuclear weapons to freeze their arsenals. The plan envisages these two steps will pave the way for the next phase of the process: the first multilateral nuclear arms reductions negotiations in history, expanding beyond bilateral U.S.-Russia negotiations to include all countries with nuclear weapons.

Some 200 dignitaries attended the three-day meeting, including former U.S. Secretary of State George Shultz, Swedish Foreign Minister Carl Bildt, Brazilian Foreign Minister Celso Amorim, and U.S. Under-Secretary of State for Arms Control Ellen Tauscher.

Thomas Pickering, former Under Secretary of State for Political Affairs in the Clinton administration who is also a leader of Global Zero, said in an interview with Xinhua that the United States and Russia possess some 6,000 to 7,000 nuclear warheads each, some 95 percent of all nuclear weapons on the planet.

"Russia and the United States are obviously going to have to take the lead and move toward very low levels" regarding their nuclear weapons, Pickering said.

Sergei Prikhodko, Russian presidential aide, said Wednesday Russia and the United States could clinch a replacement for the START in March or April.

The START, signed in 1991 between the Soviet Union and the United States, obliged both sides to reduce the number of their nuclear warheads to 6,000 and delivery vehicles to 1,600. It expired in December last year.

U.S. President Barack Obama and his Russian counterpart Dmitry Medvedev agreed last July to slash each country's nuclear warheads to 1,500 and 1,675 and delivery vehicles to 500 and 1,000 respectively.