At around 9 p.m. local time on Monday, a 17-year-old Muslim refugee from Afghanistan walked into a regional train in southern Germany with an ax and began attacking people indiscriminately. Four Hong Kong tourists were wounded, two of them critically suffering from an “acute life threatening wound.” Another woman, a local German, was grievously injured while walking her dog. The attack occurred in Bavaria, near Würzburg. Police shot and killed the suspect upon arriving at the scene.

Investigators found a hand-drawn Islamic State flag after raiding the suspect’s apartment in the hours following the horrific incident. On Tuesday afternoon, ISIS officially claimed responsibility for the attack. The jihadist group released a video showing a young man that appears to be the German-train terrorist vowing to carry out “martyrdom” operations in his newly adopted European country. “I will do a martyrdom operation in Germany today,” says the man in the traditional Afghan language of Pashto. “God willing, you will be targeted in your villages, in your cities, in your airports, in your streets. The Islamic caliphate is strong enough to target you everywhere, even in your Parliament.”

He added that ISIS operatives are settling in “infidel” countries across the globe in order to massacre local populations. “Wake up and support the caliphate,” he tells his fellow Muslim brothers before pledging allegiance to ISIS leader Abu Bakr al-Baghdadi.

German officials are still trying to determine the veracity of the chilling video, although intelligence experts suggest that the digital jihadist manifesto is real.

Before the video was released, ISIS announced the success of its latest terrorist attack in Germany via its propaganda site Amaq News Agency. “It called the Afghan teenager an ‘Islamic State soldier,’ using language similar to its claim of responsibility for the Bastille Day attack in Nice, France, that killed 84 people on Thursday,” reports The New York Times.

The vicious attack has once-again shined the spotlight on the Muslim refugee crisis in Germany. In fact, it was eerily reminiscent of the last train attack dating back to May when a 27-year-old German-Muslim man killed one man and injured three others in a spontaneous terror attack against innocent commuters. He was shouting “Allahu akbar” repeatedly during the attack.

However, Germany has so far evaded the threat of a large-scale, coordinated jihadist assault. Unlike its neighbors France and Belgium, Germany has only suffered from individual, isolated incidents. That may change very soon, though, as more refugees potentially importing anti-Western ideologies settle into German neighbors and develop contacts with established Islamist networks.

To close observers, the recent attacker’s background shouldn’t be surprising.

Bavarian State Criminal Police say that the 17-year-old Muslim refugee crossed into Germany on June 30, 2015. He arrived without his parents and registered for asylum in Passau. He received a temporary residency permit shortly after.

Monday’s attack will undoubtedly place increased political pressure on migration-friendly German Chancellor Angela Merkel to seal the border and stem the flow of refugees from Islamist hot-spots.

As the Times notes, “More than 60,000 unaccompanied minors were registered as asylum seekers in Germany last year, and more than half of the approximately 15,000 in Bavaria were from Afghanistan.” In total, 1.5 million refugees have applied for asylum in the last 18 months. Most of them come from war torn Muslim-majority countries

Monday’s attack will undoubtedly place increased political pressure on migration-friendly German Chancellor Angela Merkel to seal the border and stem the flow of refugees from Islamist hot-spots. As The Daily Wire’s Ben Shapiro noted, Merkel has already been expressing reservations about her own asylum policy following reports of mass sexual assault and rape by migrants in Cologne. It may be too little, too late. Merkel’s poll numbers have been slipping for months and Monday’s attack may have been signaled the death knell to her political future. Now the pendulum may swing sharply the other way as far-right xenophobic populist parties gain increasing support by a public that feels unprotected and unsafe after Merkel’s heavy-handed multicultural experiment.