Duc Anthony Nguyen, 29, Littleton, Colo., pleaded guilty on Monday in district court in Minot to three Class A felony charges of uploading child pornography to Twitter and to five Class C felony charges of possession of child pornography.

The pleas were made on an open plea basis, meaning that Judge Gary Lee could sentence him as he chooses when Nguyen is sentenced on Dec. 7. Each Class A felony carries a maximum sentence of 20 years in prison and a $20,000 fine and each Class C felony carries a maximum sentence of five years in prison and a $10,000 fine. The state dropped seven other charges against Nguyen, including two Class A felonies and five Class C felonies. Ward County Assistant State’s Attorney Ashlei Neufeld and Nguyen’s defense attorney, Robert Bolinske, also will make a joint sentencing recommendation to the judge at that time. Nguyen will also be ordered to register as a sex offender.

Lee ordered Nguyen taken into custody immediately after he changed his pleas. Lee also ordered a pre-sentence investigation and a sex offender evaluation for Nguyen.

Nguyen uploaded sexually explicit images to Twitter of girls who appeared between the ages of 8 and 16. He also possessed sexually explicit images of minor girls on his cell phone. He was charged after police received a tip from the Minot Air Force Base OSI Division, which had initially received the report from the National Center for Missing and Exploited Children. Police obtained a search warrant and searched Nguyen’s southeast Minot residence on Feb. 2, 2017. At the time, Nguyen was serving in the Air Force.