Bulgarian officials announced that the Lebanese militant group Hezbollah was behind a bus bombing that killed five Israeli tourists last summer, a ruling that could force Europe to officially sanction the group. Two men, one with an Australian passort and one with a Canadian passport, set off a bomb next to a tour bus at an airport in Burgas on July 18. The Israeli government immediately accused the Iranian-backed Hezbollah of being behind the attack, but no formal ruling had been made before today, when Bulgaria’s interior minister, Tsvetan Tsvetanova, said there was "a well-founded assumption" the conspirators belonged and were financed by the group.

The ruling could drastically change the dynamic between the European Union and Hezbollah, which has tacitly enjoyed support throughout most of the continent, even as the United States has declared it a terrorist organization. (The Obama administration said this morning that it "commends" Bulgaria for a "professional and comprehensive investigation.") Despite Hezbollah's attacks on Israel and its pseudo-alliance with Iran, the Europeans have generally taken a hands-off approach with the group, allowing members to fundraise and recruit and Europe, then send money back to Lebanon to support the group's activities, both legitimate and military. That truce was allowed to continue as long as Hezbollah was not a direct threat to Europeans, but now that Hezbollah can be directly linked to a terrorist attack on the continent, it may be quite difficult for European governments to look the other way much longer.

Should Europe decided to join the U.S. and level sanctions on Hezbollah, that could mean the freezing of bank accounts, which would dry up major sources of revenue for the group. That's a situation leading nations like France and Germany had sought to avoid, mostly to prevent taking sides in the Middle East crisis, and partly out of fear that it could make themselves a target for reprisals. There are thousands of Hezbollah supporters living and working in Europe already, and no one is eager to make them an enemy. The question is: Are Europeans less eager to let Hezbollah kill tourists on their soil and get away it?