Six F-16 fighters from the 555th Fighter Squadron from Aviano Base, Italy, have arrived in Poland to augment the U.S. military’s presence there amid regional tensions following Russia’s Feb. 28 incursion into Ukraine, officials said.The fighters landed on Thursday afternoon and another six F-16s are expected to arrive at Lask Air Base, Poland, by the end of the week, officials said. In addition to the 12 fighters, roughly 150 airmen will augment the ongoing training mission at the base.

A small team of roughly 10 airmen is permanently stationed at Lask Air Base, which hosts two-week training rotations for F-16 crews. It is not known how long the F-16s and airmen will stay in Poland, said Defense Department spokeswoman Eileen Lainez.