Military alliance NATO said it supported member the Czech Republic as it investigates Russia's "malign activities" on its territory and that this followed a pattern of "dangerous behavior" by Moscow, a NATO official said on Sunday.
Prague is expelling 18 Russian diplomats over suspicions that Russian intelligence services were involved in an ammunition depot explosion in 2014.
"This follows a pattern of dangerous behavior by Russia. We express our sympathy to the loved ones of the victims of the explosion in Vrbetice. Those responsible must be brought to justice," the NATO official said.