Diplomatic relations between Russia and the Czech Republic are being strained by accusations of spying.

On Tuesday, Russia ordered two Czech diplomats to leave the country. It did so in response to the Czech Republic’s expulsion of two Russian diplomats the day before. The Russian diplomats were accused of espionage. Russia’s Foreign Minister, Sergei Lavrov, has called this an act of provocation.

The Czech intelligence service issues frequent warnings about Russian espionage. It says the Russians are trying to obtain information about a rocket shield that, much to Moscow’s displeasure, the United States wishes to deploy in the Czech Republic and Poland.

Photo of the Kremlin in Moscow by CanadaGood (flickr)