Latvia says it will expel a Russian diplomat for trying to access secrets about the Nato defence alliance.
Latvia was among three Baltic states that joined Nato in March
A foreign ministry spokeswoman said the Russian ambassador had been told the diplomat must leave within 72 hours.
It is the first time that the former Soviet republic has expelled a diplomat since it regained independence in 1991.
Latvia, Lithuania and Estonia joined Nato late last month and are among the 10 countries that will join the European Union on 1 May.
Russia's post-Communist relations with the three Baltic states have been strained and Moscow has said their Nato membership could be seen as a threat.
The Latvian government did not release information on the diplomat - but a foreign ministry spokeswoman told AP news agency the Russian was being expelled for "attempting to find out about Nato military infrastructure".
Russian foreign ministry officials have not commented on Latvia's decision.
It is the third time this year that a Russian diplomat has been expelled by a Baltic country.
Lithuania ordered three Russian diplomats to leave on suspicion of espionage at the end of February.
Vilnius accused them of trying to buy documents related to Nato and the EU.
In March, Estonia expelled a pair of Russian diplomats for spying.