The United States and Russia signed a landmark disarmament treaty today they hope will herald better bilateral ties and raise pressure on countries seeking nuclear weapons to renounce such ambitions.
Presidents Barack Obama and Dmitry Medvedev signed the pact at a ceremony in the mediaeval Prague Castle after talks that covered nuclear security, Iran's nuclear programme and an uprising in the strategic Central Asian state of Kyrgyzstan.
The successor to the 1991 Strategic Arms Reduction Treaty (START I) will limit operationally deployed nuclear warheads to 1,550 within seven years.
However, it does not limit shorter-range tactical nuclear weapons.
Both major nuclear powers needed to show they were serious about reducing their vast stockpiles to lend weight to efforts to curb the atomic ambitions of countries such as Iran and North Korea, and avoid accusations of hypocrisy.
Mr Obama said the treaty would halt the deterioration in Russian-US relations.
"Together, we have stopped that drift," Mr Obama said, with Mr Medvedev at his side. "We are working together at the United Nations Security Council to pass strong sanctions on Iran and we will not tolerate actions that flout the NPT," he said, referring to the Nuclear Non-Proliferation Treaty.
Mr Obama also said he expected to secure tough new sanctions on Iran this spring over Tehran's disputed nuclear programme.
The West suspects Iran is using its civilian nuclear programme to covertly build nuclear weapons, a charge Tehran denies. It says it wants nuclear power to generate electricity and allow it to export more of its oil and gas.
The United States and its European allies want to curb the Islamic state's nuclear activities and are pushing for new UN-backed sanctions against Tehran.
A White House spokesman said after the treaty was signed that Mr Medvedev will visit the United States in the summer to discuss a range of issues including economic cooperation.
"We...discussed the potential to expand our cooperation on behalf of economic growth, trade and investment, and technological innovation, and I look forward to discussing these issues further when President Medvedev visits the United States later this year," Mr Obama said after the signing ceremony.
Mr Obama said he also hoped to start a dialogue on further arms reductions.
"As I said last year in Prague, this treaty will set the stage for further cuts. And going forward, we hope to pursue discussions with Russia on reducing both our strategic and tactical weapons, including non-deployed weapons," he said.
He said he and Mr Medvedev agreed to expand discussions on missile defence, a thorny issue in the two powers' relations.
"This will include regular exchanges of information about our threat assessments, as well as the completion of a joint assessment of emerging ballistic missiles," he told an audience of Czech officials, diplomats and reporters. "And as these assessments are completed, I look forward to launching a serious dialogue about Russian-American cooperation on missile defence."
Mr Medvedev said disagreements over missile defence remained, but he said he hoped a compromise could be reached.. Mr Medvedev will first travel to Washington next week, for a two-day nuclear security summit.
NEW START TREATY ON STRATEGIC ARMS MAIN POINTS
RESETTING RELATIONS
The new treaty is a successor to the 1991 Strategic Arms Reduction Treaty (Start), which expired in December. It is seen as a major step to improving Russia-US relations after years of tension that peaked following Russia's war with US-supported Georgia in 2008.
CUTTING DEPLOYED WARHEADS
The treaty reduces the numbers of deployed warheads from previously agreed levels, but still leaves Russia and the US with enough nuclear weapons to easily assure their mutual annihilation.
WARHEADS
The pact limits the number of operationally deployed nuclear warheads to 1,550, down nearly two-thirds from the original Start treaty, and 30 per cent lower than the limit of the 2002 Moscow Treaty.
LAUNCHERS
The pact limits to 800 the number of deployed and non-deployed intercontinental ballistic missile (ICBM) launchers, submarine- launched ballistic missile (SLBM) launchers and heavy bombers equipped for nuclear armaments.
MISSILES
The pact limits the number of ICBMs, SLBMs and deployed heavy bombers equipped for nuclear armaments to 700.
RATIFICATION
The treaty must be ratified by a two-thirds majority of the US Senate. The US says it does not expect opposition, because the treaty does not put limits on US missile defence plans. Analysts believe opposition Republicans could seize upon the treaty's ratification process as a chance to brand Mr Obama as soft on defence.
Reuters