Poland has arrested 18 people accused of pursuing hostile activities or sabotage on behalf of Russia and Belarus.
One of the schemes allegedly included plans to assassinate Volodymyr Zelenskyy, the interior minister said.
Ten of those arrested since December were directly involved in planning various forms of sabotage across Poland, Tomasz Siemoniak told a news conference.
Authorities in Poland have linked some recent arsons or attempted arsons to Russian-sponsored agents.
Mr Siemoniak said that acts of sabotage were apparently part of a wider plan that also includes cyberattacks, pushing migrants in Belarus to cross into Poland and threatening the security of the country.
"We have no doubt that on the bidding of a foreign country, Russia, there are some people active who are ready to threaten the life, health and property of the Polish citizens," Mr Siemoniak said.
