New Orleans attack came as officials warned of an escalating threat of international terrorism

The truck attack in New Orleans by an Army veteran inspired by the Islamic State group unfolded amid months of warnings by officials about a resurgent terrorism threat. FBI Director Christopher Wray has said he could not think of another time in his career "where so many different kinds of threats are all elevated at once.” But one thing notable about the New Year's Day attack is that the culprit didn't coordinate with international operatives, nor is he known to have been part of a broader plot. Instead, he embodied a longstanding concern: the threat from homegrown extremists who radicalize on their own before committing mass violence.