ON FEB. 5, after more than six months of investigations, the Bulgarian government announced that it believed Hezbollah was responsible for the attack last July that killed five Israeli tourists and a Bulgarian bus driver and injured dozens more in the resort town of Burgas. This report is significant because a European Union member state, Bulgaria, explicitly pointed a finger at Hezbollah and lifted the veil on the group’s continued terrorist activities. Europe can no longer ignore the threat that this group poses to the Continent and to the world.

The attack in Burgas was despicable. The Israeli tourists had just arrived at the city’s airport and were boarding a bus for the Black Sea coast. A young man wearing a disguise tracked the tourists’ movements, placed a bag with an explosive device in the cargo compartment of the bus and then walked away. The device exploded, killing six people, as well as the bomber.

The bomber’s death was probably not part of Hezbollah’s original plan. The group has always tried to employ strict operational security and most likely never intended for its involvement in this attack to be revealed.

But evidence recovered from the bomber’s body included a fake Michigan identification card produced in Lebanon. Elsewhere in Bulgaria, investigators discovered that operatives used two other fake Michigan IDs. These led them to the true names of the bomber’s two accomplices. They traveled to Bulgaria using Australian and Canadian passports and then returned to Lebanon using a circuitous route to hide their trail. After sharing information with Australian and Canadian security officials, Bulgaria’s government stated that it believed both of these operatives were tied to Hezbollah’s military wing.

If not for the accidental death of the bomber, there would very likely still be a debate over who conducted this terrible attack. But the Bulgarian investigation has once again proved to the world what Hezbollah has tried for years to hide: that it remains engaged in international terrorist attacks against civilians.

Hezbollah first gained notoriety in 1983 after bombing the United States Embassy in Beirut — an attack that killed 63 people. Shortly thereafter, Hezbollah bombed the American and French Marine Barracks in Beirut, killing 241 Americans and 58 French service members with one of the largest explosive devices ever detonated during a terrorist attack.

Throughout the 1980s and 1990s, the group conducted kidnappings and airplane hijackings, two bombings in Buenos Aires, several in Paris and an attempted bombing in Bangkok. In 1996 it assisted in the Khobar Towers attack in Saudi Arabia, which killed 19 Americans. Thanks to this bloody record, in 1997 Hezbollah was among the first groups added to the State Department’s list of foreign terrorist organizations.

Over the last decade, Hezbollah has worked assiduously to obscure its terrorist pedigree and convince the world that it is interested only in politics, providing social welfare services, and defending Lebanon. But it is an illusion to speak of Hezbollah as a responsible political actor. Hezbollah remains a terrorist organization and a destabilizing force across the Middle East.

Since 2011, the group has murdered civilians in Bulgaria, seen its activities disrupted in Cyprus and Thailand, and worked to plot attacks elsewhere. It is helping to prop up the brutal regime of Bashar al-Assad in Syria; and it acts as a proxy for Iran’s Islamic Revolutionary Guards Corps in the region and beyond. In doing so, Hezbollah is putting the well-being of Lebanon and its people at risk.

Now that Bulgarian authorities have exposed Hezbollah’s global terrorist agenda, European governments must respond swiftly. They must disrupt its operational networks, stop flows of financial assistance to the group, crack down on Hezbollah-linked criminal enterprises and condemn the organization’s leaders for their continued pursuit of terrorism.

The United States applauds those countries that have long recognized Hezbollah’s nefarious nature and that have already condemned the group for the attack in Burgas. Europe must now act collectively and respond resolutely to this attack within its borders by adding Hezbollah to the European Union’s terrorist list. That is the next step toward ensuring that Burgas is the last successful Hezbollah operation on European soil.