The overall goal of the NATO initiative, undertaken in the light of the Ukrainian crisis, is to reassure the allies of the NATO eastern flank, and to maintain collective defense capabilities.

Earlier on, the Thunderbolts were stationed (temporarily) at the Polish Powidz Airbase. Notably, this time the Warthog detachment is larger (includes 12 examples), and the deployment itself is to be longer, as it is going to last until the end of July, according to the rumors.

http://www.businessinsider.com/the-us-just-deployed-a-bunch-of-a-10-attack-planes-to-poland-2015-7