It finally happened. Syria’s civil war has officially spilled into Lebanon, and the two sides are using mass casualty terrorism against one another.

Earlier this month, a car bomb exploded in Hezbollah’s stronghold in the suburbs south of Beirut, killing dozens And this week, at least 47 people were killed and more than 500 wounded when two car bombs exploded next to mosques in the predominantly Sunni city of Tripoli, Lebanon’s second-largest.

This wasn’t inevitable, exactly, but it wasn’t hard to foresee.

If you divide the hostile factions into two blocs, it’s obvious who is responsible for each of these terrorist attacks.

Somebody associated with the Free Syrian Army—and by extension the Middle East’s Sunnis—detonated the car bomb in Hezbollahland, a Shia area that is generally on side with Syria’s Bashar al-Assad and the Iranian government.

Meanwhile, somebody associated with the so-called “Resistance Bloc,” the Syrian-Iranian-Hezbollah axis, attacked the two mosques in Tripoli and killed all those people.

But Lebanon is the kind of place where a variety of different groups could theoretically be responsible for any one given car bomb.

The Free Syrian Army has been threatening for months to come after Hezbollah in Lebanon unless it withdraws its forces from Syria. The same goes for the Al Qaeda-linked Jabhat al-Nusra. Lebanon itself has no shortage of radical Sunnis—including a small number of Salafists—who wouldn’t flinch at terrorizing the terrorists in their own nest.

The Tripoli bombs could have been set by Hezbollah. Or maybe Syrian intelligence agents. Possibly the Syrian Social Nationalist Party. They’re all terrorists and they’re all on the same side.

Supposedly a man named Sheik Ahmad al-Ghareeb has been arrested for the Tripoli bombs. He’s a Sunni with alleged ties to Hezbollah, and word has it he was caught on surveillance cameras. That would make him ideal. Hezbollah and the Syrians could then say to the Sunnis, one of your own people did this to you, so don’t go blaming or retaliating against us.

But the number of Lebanese Sunnis who sympathize with Hezbollah and the Assad family is vanishingly small. It’s not zero, but it’s close. Finding someone from the Sunni community who is willing to blow up two of his “own” mosques would be monumentally difficult. So we shouldn’t swallow this story yet. In Lebanon, though, anything’s possible.

If al-Ghareeb is guilty, however, and he is who they say he is, his crime still leads back to Hezbollah which remains, as always, at the end of the day, a terrorist organization.

For forty years now, terrorism has been Syria’s only real export. It’s still exporting terrorism even while engulfed in a war. And it’s suffering more terrorism now than anyone else. Hezbollah pioneered the use of the car bomb in the Middle East. Now it knows what it feels like to be on the receiving end of its weapon of choice. So there’s some twisted karmic justice here of a sort.

But the longer the war in Syria goes on (and it could go on for years even after the Assad regime goes down the garbage disposal), the more likely this war will become a full-blown regional conflagration that could suck in more nations than it already has.