KALISZ, Poland — For evidence of how much President Vladimir V. Putin of Russia has jangled nerves and provoked anxiety across Eastern Europe, look no farther than the drill held the other day by the Shooters Association.

The paramilitary group, like more than 100 others in Poland, has experienced a sharp spike in membership since Mr. Putin’s forces began meddling in neighboring Ukraine last year.

Thirty students took an oath to defend Poland at all costs, joining nearly 200 other regional members of the association — young men and women, boys and girls — marching in formation around the perimeter of the dusty high school courtyard here. They crossed Polish Army Boulevard and marched into the center of town, sprawling in four long lines along the edge of St. Joseph’s Square.

Gen. Boguslaw Pacek, an adviser to the Polish defense minister and the government’s chief liaison with these paramilitary groups, marched with them. He has been making the rounds in recent months of such gatherings: student chapters like this one, as well as groups of veterans, even battle re-enactors.