When attempting to book a flight with Turkish Airlines from Cancun to Istanbul in October, I get a warning that "Sale of passenger tickets on this route is subject and conditioned to a prior authorization from the United Mexican States".
What does this actually mean? Who needs approval? Is it just that I need to get a visa to Mexico in order to get on the flight or is it something else? Trying to google the phrase doesn't really tell me much, so hopefully someone here will know what the warning means.