WARSAW, POLAND: Hundreds of members of pro-defense forces marched in downtown Warsaw on Thursday to show their readiness to defend Poland if needed, amid concerns over the conflict in neighboring Ukraine and Russia's role in it.

"We have come here to tell Poland that we are ready to defend her and to see to the security of our countrymen in time of need," retired Gen. Boguslaw Pacek said before the parade.

Pacek is the head of the Federation of Pro-Defense Organizations and their liaison with the professional military. The federation was formally initiated in cooperation with the armed forces in March, in response to grassroots actions by ordinary Poles and paramilitary organizations.

It includes scouts and high school students who want to join the police and the military, or to support them in times of peace or conflict. They draw inspiration from pre-World War II educational and sport organizations that were preparing young Poles to help defend the country and who later fought in the clandestine Home Army and in the 1944 Warsaw Uprising against the Germans.

Pacek said around 50,000 people belong to the federation now, and expects the number to grow to about 100,000 in the next year.

"In a very responsible way, with the army's help, we want to prepare the federation members to act as paramilitaries in the case of a war crisis," Pacek said.

Their first nationwide rally marked the anniversary of the Sept. 17, 1939 Soviet invasion of Poland, which was defending itself against Nazi Germany at the time, in the initial stages of World War II. The timing highlighted the concerns over unrest across Poland's and the European Union's eastern border.

Soviet aggression remains a "warning to all the future generations concerned over Poland's security," Defense Minister Tomasz Siemoniak said.

Hundreds of uniformed young people and paramilitaries marched in front of the Tomb of the Unknown Soldier while a military band was playing.