Leaders shake on deal to cut nuclear arsenals

Tenaciously negotiated by even the leaders themselves, the treaty

commits them to slash the number of strategic nuclear warheads by a third and more than halve the number of missiles, submarines and

bombers carrying them.

In a lavish chamber within Prague's presidential castle complex, the two presidents put their names to history. The treaty must be now be ratified by Russia's parliament and by the US Senate, where the White House lobbying effort is under way.

"Today is an important milestone for nuclear security and non-proliferation, and for US-Russia relations," Mr Obama said.

Mr Medvedev hailed the signing as a historic event that would open a new chapter of co-operation between the countries.

The new treaty will shrink the limit of nuclear warheads to 1,550 per country over seven years.

That still allows for mutual destruction several times over. But it is intended to send a strong signal that Russia and the US – which between them own more than 90 per cent of the world's nuclear weapons – are serious about disarmament.

"The result we have obtained is good," Mr Medvedev said.

Inside the hall, the anticipated moment came as the two presidents picked up their pens, glanced at each other and grinned as they signed several documents, with aides transferring the papers back and forth so all would have both signatures.

When it was done, the leaders seemed momentarily at a loss, with Mr Medvedev flashing a smile and a shrug before they stood to shake hands.

Mr Obama said the treaty set a foundation for further cuts in nuclear arms.

And he pledged more conversation with Mr Medvedev about the US Europe-based missile defence plans, which remain a sticky issue between the countries as the US moves ahead.

Mr Obama said the missile defence system being considered is not aimed at changing the "strategic balance" with Russia but rather as a way to counter launches from other countries.

Mr Medvedev said he was optimistic about reaching a compromise.

The treaty opens the way for further cuts. US secretary of state Hillary Clinton said on Tuesday that Mr Obama has instructed his national security team to pursue another round of arms reduction talks with Russia to follow up on the replacement for the 1991 Strategic Arms Reduction Treaty being signed yesterday.

The aim would be to conduct wider talks to include for the first time short-range US and Russian nuclear weapons as well as weapons held in reserve or in storage.

Beyond reducing nuclear arsenals, the US sees "New START" as a key part of efforts to "reset" ties with Russia, which had become badly strained under the Bush administration, and engage Moscow more in dealing with global challenges.

Among these is Iran's defiance of UN Security Council demands that it curb its nuclear programme to ease fears that it seeks to make nuclear arms.

The pact is only part of the Obama administration's nuclear strategy and it was signed only days after the White House announced a fundamental shift that calls the spread of atomic weapons to terrorists or rogue states – nations such as North Korea or Iran that do not abide by non-proliferation rules – a worse menace than the Cold War threat of mutual destruction.

On Tuesday, in detailing key components of an in-depth nuclear strategy review: Mr Obama said: "For the first time, preventing nuclear proliferation and nuclear terrorism is now at the top of America's nuclear agenda."

The chances of enlisting China, an even more stubborn opponent of Iran sanctions than Moscow, now improve with the treaty signed.

Opposition takes over Kyrgyzstan

An opposition coalition in Kyrgyzstan has formed an interim government that will rule for six months.

Opposition leader Roza Otunbayeva said she will head the government that dissolved the parliament and will take up legislative duties.

She told a news conference that the new government will conduct negotiations with President Kurmanbek Bakiyev, who left the capital and is presumably in hiding.

The opposition seized Kyrgyz government headquarters yesterday after it was stormed by protesters in clashes that left 68 dead.

Ms Otunbayeva said her government will amend laws that Mr Bakiyev changed to ensure his supporters' domination of parliament.

Kyrgyzstan hosts a US air base, Manas, an essential transit point for military supplies to Afghanistan. Flights were halted for 12 hours.