DH's sister and brother are both Marines. There has been some stuff the last few days happening that doesn't surprise me if they put a ban. Although for our wedding in August they did have to have approval. They were told had it been one of the many border towns or areas w/ the many troubles of the drug war they wouldn't have been able to go. That was when there was alot going on. But even though we were going to the Riviera and at that time I believe the only drug war death there had been one plotted out against a mexican politician. But they still had to have approval to go Mexico. SIL was able to do her paperwork a couple months out but wrote in the wrong days she'd be there and had to resubmit in the couple of weeks before the wedding but still got approval.
But she did have a hold up because she needed proof that it was her brother (something official of his saying the same last name) and that we were having a wedding. The hotel owner and our WC wrote letters for us saying that we were having a wedding, on a certain day, etc, and we sent invoices of our hotel blocks and contract w/ the hotel. As soon as they saw all of that they instantly approved her leave to Mexico