Poland on Thursday said it had expelled three Russian diplomats, following a similar move by the United States, over what Warsaw called "hostile actions" by Moscow.
Earlier Thursday the U.S. announced sanctions and the expulsion of 10 Russian diplomats in retaliation for what Washington said was the Kremlin's U.S. election interference, a massive cyber attack and other hostile activity.
The Polish foreign ministry said it had declared the three embassy staff members personae non gratae because of a "violation of diplomatic status and carrying out activities to the detriment" of Poland.
The ministry added in the statement that Warsaw "expresses its full solidarity with the decisions taken by the United States [...] regarding its policy towards Russia."
"The decisions jointly made and agreed upon [by] allies constitute the most appropriate response to the hostile actions by the Russian Federation," the ministry added.
Poland's move was the latest show of support for the U.S. after Britain summoned the Russian ambassador in the UK to express its deep concern at what it called Moscow's "pattern of malign activity."
The NATO military alliance also expressed its support for the U.S. following its "announcement of actions to respond to Russia's destabilizing activities."
The EU for its part expressed "solidarity with the United States on the impact of malicious cyber activities, notably the SolarWinds cyber operation," referring to the massive hack of U.S. government computer systems last year.
In an earlier statement Thursday, Poland's foreign ministry expressed concern over the cyber attacks.
"The consequences of these attacks extend beyond the U.S. and notably affect European countries," the ministry said.
"The steady increase in harmful activity in the cybersphere [...] has a negative influence on society, the economy and government in many countries."