By 8 a.m. on a Saturday, nearly every seat in the room was filled. There were families and office colleagues, couples holding hands, grandmothers and teenage boys. A group of eight, mothers and their teen daughters, passed around snacks, drinks and hand cream.

They had gathered at the headquarters of the 133 Light Infantry Battalion of the 13th Silesian Territorial Defense Brigade in Cieszyn in southern Poland for emergency preparedness training.

The civilian training sessions are part of a new and ambitious plan by Poland’s government to ready its 38 million or so people for the possibility of a military attack from Russia. The program, wGotowosci, or Readiness, is “the largest defense training in Polish history,” the country’s defense minister, Wladyslaw Kosiniak-Kamysz, said when announcing it in November. He hopes 400,000 citizens will complete the training by the end of this year.

As the Ukraine war grinds on in its fifth year, the threat of a belligerent Russia hangs heavy. President Vladimir V. Putin of Russia has repeatedly provoked European leaders with hybrid or “gray zone” warfare, testing the resolve of the North Atlantic Treaty Organization with disinformation campaigns, sabotage and cyberattacks.