The Saturday bombing in a crowded area in the Turkish town of Reyhanli ostensibly targeted Syrian rebels specifically and Sunni Syrian refuges generally. That the powerful twin bombings killed at least 43 people and injured another 140 people happened on Turkish soil, with indications linking it back to the Syrian intelligence agencies (who have links to Iranian Revolutionary Guards), is an escalated proxy response to the quickly deteriorating situation in Syria.
With all the talk about "red lines" - which it is worth mentioning since Turkey continues to be vocal about the chemical weapon links to Syria - the fact that they are doing state-sponsored attacks against a NATO country may mean this doesn't become Obama to start it.
If Turkey were to claim Article 4 (which they have after previous rocket attacks which killed far fewer than today's attack) or Article 5, the US along with potentially France and Great Britain could be drug into this conflict by way of our alliance obligations.
This may be an overreaction and not necessarily the best move, but if asymmetrical attacks inside Turkey against civilian targets - which are directly linked to the Syrian state - continue, there may not be a choice.
On the other front, Hezbollah boasts of increased capabilities since 2006. They claim that for now the orders are to let Israelis fly over Lebanon airspace but that the "game changing" weapons that Nasrallah previously referred to are most likely surface-to-air missiles. In 2006 the group had success against Israeli tanks with anti-tank mines, nearly sank an Israeli warship with an Iranian missile, and of course there are the much-recently talked about enhanced missiles with long range and great accuracy that Israel destroyed. Which isn't to say shipments already are in Lebanon. Iran and Syria could wage a proxy war here as well and hope to drag Israel to Lebanon and take the heat off Iran.
The long and the short is, Obama has been wise to approach it the way he has. The pundits armchair quarterback but any outcome won't be good and he would be blamed either way. With that said, the situation is very volatile. It may be out of the US control in some respects however if the Syrians decide to use terrorism against a fellow NATO ally. Things could rapidly spiral out of control and the US may not have any choice but to do things like establish a no-fly zone. No troops of course, no more invading countries, but NATO obligations may be calling one day.