The would-be terrorist who tried to blow up Brussels’ main transit hub last month had plenty of ambition, but no discernible talent. His homemade bomb, a suitcase stuffed with nails and camp-stove gas canisters, caught fire as he wheeled it into the station, sending passersby fleeing before the device could properly explode — which it failed to do.

The only casualty was the bomb-maker himself, an Islamic State sympathizer who was shot and killed as he lunged at police, armed only with his fists.

As an act of terrorism, the June 20 attempt was a merciful failure. Yet it also bore hallmarks that are becoming increasingly familiar to Western officials who monitor attacks by the terrorist group in countries around the globe: simple plots, crude weapons and inexperienced perpetrators who act alone, without apparent direction or training.

A State Department report released Wednesday underscores the persistence of the terrorist threat posed by the Islamic State, which despite military setbacks posted a record number of attacks and fatalities in 2016, surpassing all other militant groups worldwide. But at the same time the sophistication of the group’s operations is slipping, suggesting that counterterrorism measures arrayed against the militants is taking a toll, U.S. and European counterterrorism officials say.