Alvez says that he worked with Peakstone in Afghanistan. However, in S12 E14, Garcia asked him if he had ever fought in Afghanistan and he said no, that he was in Iraq. He says he was in Iraq with the Army. Given that he spent much of his FBI time working on the fugitive task force, he well may have also helped with the major crimes task force in Afghanistan when they set up bio-metrics and tracking systems for apprehending terrorists.