Turkish-Syrian border

''At any time if the United States truly wanted to strike an irreparable blow at ISIS forces, it could simply seal off the Turkish border across which the summation of ISIS’ supplies, fighters, weapons, and vehicles flow. By securing the Turkish-Syrian border to the north, and the Jordanian-Syrian border in the south, the United States could strangle ISIS out of existence in a month, if not sooner.
 * — Tony Cartalucci, US Complains as Russia Bombs Its Terrorists - New Eastern Outlook, October 1, 2015