Five years ago this month, a group of U.S. airmen boarded a bus at Frankfurt Airport in Germany. They were waiting for a ride to Ramstein Air Base about 65 miles away when a 21-year-old man outside the vehicle asked one of them for a cigarette and if they were U.S. troops on their way to Afghanistan. When the American said they were, the stranger waited until he turned around and shot him in the head.

“Allahu Akbar!” the man shouted — before entering the bus and shooting at the other Americans.

Those details emerged in the 2012 murder trial of Arid Uka, a Muslim ethnic Albanian who grew up in Germany and was born in Kosovo. He was convicted and sentenced to life in prison. Uka said during his trial that he had been radicalized by Islamist propaganda videos he had watched online, according to media coverage of his case.

The attack killed two service members — Senior Airman Nicholas Alden, 25, and Airman 1st Class Zachary Cuddeback, 21 — and wounded two others. The ambush would have been even more severe, but the shooter’s gun jammed while he was on the bus.

The case stands as one example of how U.S. troops have faced deadly situations far from the battlefield in recent history. It also prompted U.S. European Command, the military’s four-star headquarters for the continent, to issue new rules after the attack that prohibited U.S. troops from wearing their uniforms while not on bases “to the maximum extent possible,” including when traveling to and from their jobs. Doing so, the thinking went, made them obvious targets.

But from U.S. sailors being attacked by a mob in Turkey in 2014 to off-duty service members facing a gunman on a train from Amsterdam to Paris last year, U.S. service members continue to find themselves caught in the middle of violence in Europe. The latest example occurred Tuesday, when a member of the Air Force and his family were wounded in bombings that shook the airport in Brussels.

The airman, who has not been identified by the Pentagon, is a member of Joint Force Command Brunssum in the Netherlands, a NATO command focused on providing command and control to the coalition’s Resolute Support mission in Afghanistan.

In two situations since November, the U.S. military restricted travel in parts of Europe after attacks for which the Islamic State militant group asserted responsibility. The first, in Paris in November, prompted the chief of European Command, Air Force Gen. Philip M. Breedlove, to temporarily ban all non-essential travel by U.S. service members to Brussels and Paris. That ban was rescinded later in the month, but European Command added one for Turkey that remains in place.

Another travel ban was put in place for Brussels after Tuesday’s attacks. Like the earlier one, it applies to service members who want to travel while on leave or liberty. Official travel to the city is still allowed, but requires approval from a general officer, a move that ensures a larger network of commanders can track it. The restrictions don’t apply to U.S. troops assigned to diplomatic posts in Belgium but effectively prevents tens of thousands of others in Europe from traveling to an area where tensions remain high.

Other attacks on U.S. troops that did not appear to have direct links to the Islamic State have spawned a more muted response. In the 2014 case in Turkey, the sailors were in Istanbul for a port visit while serving on the USS Ross. The Turks said they were members of the Turkey Youth Union, a nationalistic group that is opposed to Turkey working with the United States and becoming a member of the European Union.

“We define you as murderers, as killers … and we want you to get out of our land,” one man said in a video capturing the incident, seconds before one of them attempted to put a bag over the head of a sailor.

In the case last year on the train, then-Airman 1st Class Spencer Stone, Army National Guard Alek Skarlatos, their friend Anthony Sadler and an American professor, Mark Moogalian, helped thwart an attack in which Ayoub el-Khazzani, a 25-year-old Moroccan, opened fire on passengers shortly after crossing into France from Belgium. Stone tackled the shooter and was stabbed in an ensuing struggle.

Authorities have said the shooter had ties to radical Islam, but his lawyers say that isn’t true and that he wanted to carry out a robbery. His weapons included a Kalashnikov rifle, a pistol and a box cutter. 

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