The crisis between Turkey and Syria intensified today. Turkey’s top military commander warned the Syrians that his country would “respond more strongly” to persistent cross-border attacks that have already killed a handful of Turkish nationals. Turkey has already responded with shelling against targets inside Syria. This threatens opening up a second front in Syria’s civil war, escalating it into a regional conflict. Both sides claim that they want no wider war, but will “defend its territory,” which in the end will look increasingly like a war.
Robert Wright explains this more thoroughly:
 Turkey could decide before long that war is preferable to the alternatives. The Syrian civil war is creating all kinds of problems for Turkey. There’s a big influx of refugees, and there’s also the Kurdish issue: Many of Syria’s Kurds hope to use the civil war as an opportunity to carve out an autonomous or even sovereign Kurdish region in Syria, and Turkey fears that this could prove contagious, emboldening Kurdish separatists in Turkey and energizing longstanding dreams of a new Kurdish nation that comprises parts of Turkey, Iraq, Syria, and Iran. Both of these issues–refugees and Kurdish nationalism–could lead Turkey to conclude that the sooner the Syrian civil war ends, the better. And helping fight it could help end it–especially if Turkey’s fellow members of NATO help out.
 Speaking of NATO: The fact that a Turkish-Syrian war could draw America into the conflict will make such a war more attractive to some backers of American intervention. That includes some influential Americans (largely, but not entirely, drawn from the crowd that got the U.S. into the Iraq war), but it also includes non-Americans, among them, presumably, the leaders of some Arab states. And the more influential players there are who want a war to happen, the more likely it is to happen.
The US already seems to be planting the flag here. The New York Times revealed today that 150 military planners and specialists are on the ground in Jordan, and have been there since May. So far they appear to be helping to manage the humanitarian crisis caused by refugees streaming out of Syria. But the forces are also “positioned should the turmoil in Syria expand into a wider conflict.”