Obama and Medvedev agree to cut back their nuclear arsenals

The new treaty – designed to replace the 1991 START accord which expired last December – would further shrink the massive stockpiles the United States and Russia amassed during the Cold War.

It would limit both sides to 1,550 warheads – about 30 per cent fewer than are currently allowed – and 700 deployed missiles and bombers.

The White House said the measure also includes tough verification measures that will enable both sides to monitor all aspects of its implementation.

Although the agreement must still be ratified by the Senate and the Russian Duma before it takes effect, presidents Barack Obama and Dmitry Medvedev plan to sign it next month in Prague – the city where last April Mr Obama delivered his signature speech on arms control committing America to the ultimate goal of "a world without nuclear weapons."

The White House said: "The presidents agreed the new treaty demonstrates the continuing commitment of the United States and Russia – the world's two largest nuclear powers – to reduce their nuclear arsenals consistent with their obligations under the Nuclear Non-Proliferation Treaty."

Mr Obama described the agreement as part of the US effort to "reset" the with Russia.

"With this agreement, the United States and Russia... also send a clear signal that we intend to lead," he said.