Countries can do more to make it difficult for individuals to leave for Iraq or Syria; a Europe-wide watch list, for example, would help. But nothing would have a greater impact than Turkey deciding that it will no longer allow itself to be a conduit, and that it will enforce United Nations Security Council Resolution 2178, which calls for stronger international cooperation against terrorism.
切断人员招募流更加关键。国家可以增加个人前往伊拉克和叙利亚的难度；比如，泛欧洲观察名单就有所助益。但影响最大的还是土耳其决定不再充当前往伊斯兰国的通道并执行呼吁加强反恐国际合作的联合国安理会2178号决议。