One of my bridesmaids is in the military. She got word last week that the active military and Department of Defense employees is restricted to go to Cancun area. She said there has been a restriction in part of Mexico for some time but it has just expanded to Cancun. The restriction is due to violence and drugs. I'll let you know when I find out more.
As far as she knows right now, if this ban is still in place during my wedding, she will not be able to attend. She is supposed to be asking her boss the specifics.