The Russian government's decision to approve the Kyoto climate change treaty has been hailed by the European Union and environmental groups.
Putin backs Kyoto - but his top economic aide opposes it
The Kyoto Protocol sets targets for greenhouse gas emissions, which many scientists believe are causing the Earth to warm at an unnatural rate.
The cabinet has sent it to parliament to be ratified, where President Putin's supporters hold a two-thirds majority.
The US, the biggest greenhouse gas producer, has not signed the treaty.
Since the US pulled out three years ago, the treaty has been dependent on Russian ratification to be binding under international law.
It must be ratified by the countries who together are responsible for at least 55% of 1990 global greenhouse gas emissions. Russia accounts for 17% of world emissions.
The BBC environment correspondent Richard Black says Russia's move is politically vital.
Our correspondent says that Kyoto was only ever a first step - now discussions on the next, more stringent target on greenhouse gas emissions can begin.
European Union Environment Commissioner Margot Wallstrom told the BBC: "We are very excited today - we have to wait [for] procedures in the Duma, but it looks very good."
And UK Environment Secretary Margaret Beckett praised the Russian move as "a vital step forwards for global efforts to tackle climate change".
Japanese Prime Minister Junichiro Koizumi added his praise, saying the "prevention of global warming is a very important and difficult issue".
Bryony Worthington of environmental campaign group Friends of the Earth expressed delight at the Russian decision, telling the BBC: "It will increase pressure on countries like the US and Australia, who have so far remained outside the only international agreement to curb greenhouse gas emissions."
Interfax news agency said that Russian ministries linked to the environment had been given three months to work out a series of practical measures arising from Russia's obligations.
Change of heart
President Vladimir Putin ended the confusion over Russia's stance in May, when he spoke of his desire to see the treaty ratified.
Some economic advisers had warned that Russia could face economic crisis if it had to cut greenhouse gas emissions.
But Russia had to cut emissions from levels set at the height of Soviet output, Dafne Ter-Sakarian of the Economist Intelligence Unit said.
This makes it unlikely that Kyoto will hurt the economy in the short term.
But the deciding factor appears to be not the economic cost, but the political benefits for Russia, correspondents say.
In particular, there has been talk of stronger European Union support for Russia's bid to join the World Trade Organization, in response to its ratification of the treaty.