Revolutions war, last thing you want is a US prisoner. Similar how ISIS is now they grab Humanitarian workers and foreign travelers to ransom them and to use them as terror fuel. Now adays if the US says No Travel to XXXX We'd just go anyway. So usually you'll find airlines pull flights if passengers become endangered in a country (If ISIS manages to for a theoretical second capture the entirety of Turkey, We would most likely embargo the New ISIS Controlled Turkey, and stop flight/boat access)