Controller reported pilot failed to follow control instructions possibly due to language barrier; which resulted in entering a higher MIA.

Narrative

[Aircraft] was at 9;000 ft. filed ZZZ ZZZ1; on this route the aircraft was clear of any MIA. When aircraft reached ZZZ1; the aircraft did not make a turn towards the East towards the ZZZ3 VOR. The aircraft continued on a southeast heading toward MIA's that were higher than the aircraft's current altitude. I questioned the Pilot if they were turning toward ZZZ2. I think it might have been a Pilot with low experience because the Pilot sounded unsure and ZZZ1 was not complying with control instructions. I climbed aircraft to 11;000. It took numerous calls to finally get Pilot to turn away from the higher MIA's. It sounded like it may have been a foreign Pilot; I believe there could have been a language barrier. I tried giving a low altitude alert; but couldn't remember the phraseology. I think having recurrent training going over these types of scenarios and practicing the phraseology would help. There is recurrent training once a year were some of this is reviewed; but I think reviewing this more than once a year would be helpful; especially with phraseology we don't use often.