The first joint training exercises in Poland for U.S. troops and their Polish counterparts are underway.

A U.S. armored brigade of 3,500 troops from Fort Carson, Colorado deployed this year to Zagan, southwestern Poland, as a deterrence force on NATO's eastern flank.

Exercises that started Monday at the Zagan Military Training Area involved land troops from the U.S. and Polish armies, tanks and armored vehicles.

Poland's President Andrzej Duda and the U.S. ambassador to Poland, Paul Jones, observed the training.

They stressed that the U.S. troops' presence was strengthening the region's security and also bilateral ties.

Duda said: "God bless Poland, God bless America, God bless American soldiers."

The force comes as reassurance to nations in the region that are nervous about Russia's growing military activity.