A 21-year-old man from Kosovo went on trial in Frankfurt, Germany, Wednesday and confessed to killing two U.S. Air Force personnel and wounding two others earlier this year.

Arid Uka admitted his guilt and apologized on the opening day of his trial, saying he had been influenced by Islamist propaganda. He added that he could not understand how he could have acted that way.

German prosecutors charged Uka with two counts of murder and three counts of attempted murder for the March 2 attack at Frankfurt airport. Uka was employed at the airport at the time of the attack. He said he came to the airport with a gun and two knives with the intention of killing American soldiers to prevent them from going to Afghanistan.

U.S. federal prosecutors have also filed murder charges against Uka. They say he chanted “God is great” in Arabic and kept shooting until his gun jammed. U.S. officials believe he acted alone and was not a part of any terrorist group.

Uka, who was arrested at the scene, faces a possible life sentence for murder and attempted murder. A verdict in the trial is not expected until early 2012.