Mindaugas Kulbis, Associated Press
A member of US Army’s 2nd Cavalry Regiment shows a gun to a young boy on a Stryker vehicle during the ''Dragoon Ride'' military exercise, in Salociai some 178 kms (110 miles) north of the capital Vilnius, Lithuania, Monday, March 23, 2015. The troops began the trek on March 21, and will travel through Lithuania, The Czech Republic and onto Germany by April 1 in an exercise designed to reinforce America's allies.

WARSAW, Poland — A U.S. army infantry convoy is driving through eastern Europe seeking to provide reassurance to a region concerned that the conflict between Russian-backed rebels and government forces in Ukraine threatens its security.

The U.S. "Dragoon Ride" convoy is attracting interest and greetings from people along its route. It started last week from Estonia and passed through Latvia and Lithuania before entering Poland on Monday.

Flying U.S. flags, dozens of Stryker and other armored vehicles from the 3rd Squadron of the 2nd Cavalry Regiment are driving down the roads on their way back to base in Vilseck, Germany. They took part in the Atlantic Resolve exercise that shows NATO's readiness to defend its members. They will stop in some Polish towns to meet local residents.

The move comes at a time when Poland is stepping up its own defenses by calling thousands of reservists for urgent military training and by hosting major NATO and international exercises this year. Also Monday, Canadian and Polish troops held exercises at a test range in Drawsko Pomorskie, in the northeast.

Bordering Ukraine and Russia, Poland says it has trust in NATO's collective security guarantees but it also harbors bad memories of defense alliances with Britain and France that failed when Nazi Germany invaded in 1939.

Adviser to the defense minister, Gen. Boguslaw Pacek, recently stressed that NATO expects its members to also build their own defenses.

In an apparent reference to Russia, Pacek said that the U.S. convoy is a sign to "those in the East" that NATO is strong and united.

Meanwhile, Poland is practicing mobilization by calling on hundreds of reservists to immediately show up for military training. In total, some 12,000 reservists are to go through various forms of training this year.