Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 8
Communication Breakdown; Situational Awareness
Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance
Human Factors
Aircraft X was flying level at 9000 ft. and I got an MIA [Minimum IFR Altitude] alert so I told the aircraft to climb to 10000 ft. to clear the MIA. I radioed him again right after to inform him I needed to vector him for some military airspace. He started to question it so I told him he would need a vector or he would need to be VFR and enter a military training complex at his own risk. I noticed that through this he was not climbing. I told him that I needed him to climb right now and that I would also need to vector him. He started to climb but had already entered the MIA box of 9300 ft. The pilot sounded as if to be a foreigner and did not take the appropriate action as directed. He was confused and his delayed response is the reason for the loss of separation. I also should have caught the MIA situation sooner.Pilot needs to take action when given a clearance.
Denver Center Controller reported observing an aircraft that received a Minimum IFR Altitude alert and climbed the aircraft but pilot was slow to respond.