Poland has arrested a Russian man accused of being hired by Moscow to kill a Ukrainian-American living in Warsaw, Prime Minister Donald Tusk said. The case matters because it suggests alleged Russian-directed violence may be extending beyond Ukraine’s battlefield into a NATO member state.

Tusk said the suspect was detained on Friday and described the intended victim as someone “inconvenient to the Putin regime”. Reuters reported that the alleged target was in Poland’s capital, Warsaw, though the available report did not provide further details about the man, the alleged plot or any charges.