Russian President Vladimir Putin has signed a deal creating an economic union with Belarus and Kazakhstan, with Ukraine conspicuously absent after it turned its back on Moscow.
"Russia, Belarus and Kazakhstan are going over to a fundamentally new level of cooperation," Putin said at the signing ceremony in the Kazakh capital of Astana on Thursday.
The economic union project is hugely symbolic for Putin, who in 2005 called the breakup of the Soviet Union "the biggest geopolitical disaster" of the 20th century.
But the union crucially failed to secure the participation of Ukraine, a country of 46 million with a potentially strong industrial sector.
"We lost some along the way: I mean Ukraine," Belarussian President Alexander Lukashenko said at the signing ceremony.
"I am sure that sooner or later the Ukrainian leadership will realise where its fortune lies."
Ukraine plunged into an unprecedented crisis last November when then-President Viktor Yanukovych pulled out of signing an Association Agreement with the European Union.
Months of street protests led to Yanukovych's ouster and the installation of pro-Western leaders determined to steer the country out of Moscow's orbit.
The Eurasian Economic Union, which is to come into force on January 2015, is designed to strengthen ties between the ex-Soviet countries which have already joined forces in a customs union created in 2010.
The alliance will follow a much looser Eurasian Customs Union that Russia formed with the two ex-Soviet nations in 2010 in an effort to build up a free trade rival to the 28-nation EU bloc.
"This union is economic and does not affect the countries' sovereignty," said Kazakh President Nursultan Nazarbayev.
