Syria

Restricting the group's access to banks has forced it to use riskier methods of moving money, but it still draws major revenue from extortion and other sources.

Whether the Paris terrorists were funded by their own activities in Europe or ISIS revenues from Syria and Iraq, the fact remains that small sums of money can facilitate painfully successful attacks, so cutting off the group's finances is no panacea.

With a limited ground force, increased airstrikes, and more reasonable rules of engagement, the United States and its allies could establish safe zones where interim government could be established and moderate forces could be trained to control territory once the Islamic State is expelled.

Refugee-baiters and their proposed policies will only further undermine future European security.

An Iraq expert and a top Kurdish intelligence official provide an on-the-ground account of how the coalition can mobilize greater Kurdish military support for the fight against ISIS.

Russia has greatly complicated an already-fraught situation by picking a fight with Syria's majority Sunni rebels and tripping into other regional players' spheres of influence.

Neighboring countries present dangers, privations, and complications not present in Europe, and after hearing about these problems or experiencing them firsthand, many desperate Syrians have decided to head for the continent.

The following summary of the Syrian conflict by Andrew J. Tabler appeared as a sidebar to the October Atlantic Monthly article, " The Syrian Civil War: What?" The Syrian Civil War is arguably the worst humanitarian crisis since the Second World War, with over a quarter million killed, roughly the

Sustaining U.S. and Turkish assistance to the Syrian Kurds is crucial to blocking ISIS and stemming Russian influence, as is resolving Ankara's Kurdish problems at home, but sending heavy weapons to the PYD would likely have unintended consequences.