The first Ukrainian forces learning how to use a new U.S.-based weapons system have returned to their country after being trained in Grafenwoehr, Germany, defense officials said Wednesday.

The soldiers were artillery forces who were already familiar with Howitzer tanks and armored vehicles on their own system but were trained to use a U.S.-based system as well. A second wave is currently being trained, according to Brig. Gen. Joseph Hilbert, commander of the 7th Army Training Command.