KEY incidents of diplomatic expulsions between Russia and the West since the collapse of the Soviet Union:
1992: France expelled four Russian diplomats after uncovering an industrial espionage ring. Russia did not retaliate.
1994: The US expelled a top Russian intelligence officer after discovering that CIA officer Aldrich Ames had spied for the Soviet Union and then Russia for years.
Moscow retaliated by expelling a US diplomat. The Ames case is considered one of the most damaging ever for the US.
1996: Russia expelled four British diplomats accused of spying. Britain threw out a similar number.
1998: An espionage case leads Norway to expel two Russians, and Russia to retaliate by expelling two Norwegians.
A spying row between Russia and South Korea also led to five expulsions on each side.
2001: The US threw out 49 Russians after unmasking Robert Hanssen, an FBI officer who had been spying for Moscow.
Russia retaliated by expelling a similar number of Americans. President Vladimir Putin accused the US of 'spy mania'.
2002: Sweden expelled two employees from the Russian embassy in Stockholm over allegations that they had spied on Ericsson, a telecommunications equipment maker.
In response, Russia declared two Swedes to be persona non grata.
AGENCE FRANCE-PRESSE