By Steven Eke
BBC Russian affairs analyst
Russia stopped producing chemical weapons in 1987
Russia has opened a facility in the Ural Mountains that will decommission vast stocks of its chemical weapons.
It has been part-funded by the US as part of a programme to dismantle what was the world's biggest arsenal of chemical and biological weapons.
The factory at Shchuchye is to dispose of 5,500 tonnes of chemical weapons, including the nerve gases VX and Sarin.
The gases will be neutralised, before being sent for long-term storage in concrete-lined underground bunkers.
Scientists and officials from Russia, the US, the UK, France and Canada attended Friday's ceremony to open the Shchuchye chemical weapons decommissioning facility, which is the size of a small town.
Moscow has already destroyed about 30% of its chemical weapon stockpile
The governor of the local Kurgan region said it was an event of global importance.
The plant is some 1,600km (995 miles) to the east of Moscow, deep in the Ural Mountains.
It is tasked with destroying 5,500 tonnes of chemical weapons including VX and Sarin, the mainstays of the Soviet Union's chemical weapon programme.
They are currently stored in shells, which will be drained of the toxic agents. These will be neutralised, then turned into bitumen salt mass. The waste will be sent for long-term storage in concrete-lined, subterranean bunkers above the groundwater level.
The opening of the plant is an important symbol of US-Russian co-operation, at a time when both countries speak of the need to restart their relationship.
One third of the finance to build the facility in Shchuchye - about $1bn - was provided by the US as part of its Co-operative Threat Reduction (CTR) programme.
This provides money and technical expertise for dismantling of weapons of mass destruction in the countries of the former Soviet Union. The remainder of the finance comes from Russia and the EU.
Russia stopped producing chemical weapons in 1987, before the end of communism. In 1997, its stockpile still stood at some 40,000 tonnes.
Under the Chemical Weapons Convention (CWC), which it signed in 1993, Russia is obliged to dismantle its stockpile entirely by 2012. By May, Russia had destroyed 30%, half what the US had managed.
Russian officials insist they are on schedule to meet this deadline, but US officials say Russia is badly behind and predict its weapon destruction programme will be completed no earlier than 2027.