CHICAGO (AP) — U.S. citizenship has been denied an army veteran with a green card who faces deportation because of a 2008 drug conviction.

The decision Thursday by immigration officials to deny citizenship to Afghan war veteran Miguel Perez Jr. means he can be deported to Mexico at any time.

The 39-year-old Perez Jr. petitioned immigration officials to be granted citizenship retroactive to when he joined the military in 2001.

Perez served two tours in Afghanistan. He says he mistakenly thought he became a U.S. citizen when he took an oath to protect the nation.

Perez was taken into custody by Immigration and Customs Enforcement officers after he served seven and a half years in prison for a non-violent drug charge. He is being held in a Wisconsin detention center where he awaits deportation.