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.”
Their goal may be more to keep Jordan out of any regional conflict, rather than to get involved in it. Jordan and Syria have had their own cross-border skirmishes, but nowhere near on the level of Turkey. The crucial part of this is Turkey’s status as a NATO ally; the Turks would get the backing of NATO if they requested it to fight Syria.
Meanwhile the civil war continues to rage inside Syria, with rebel forces capturing a trading post of a town in Idlib province. Syria feels they must fight this internal rebellion and the border in Turkey, which has been supplying the rebels and capturing border posts. Turkey has never attempted to stop the supply for the Syrian rebels, so in a real sense the cross-border war has already begun.
How anyone manages this is unknown, but it does look like these Arab powers are sliding into war.