evidence: In October, after the deaths of four American army soldiers in an ambush in Niger focused attention on a build-up of hundreds of American forces there, a deployment that began under Obama and expanded under Trump, Mattis testified that the administration had sent the troops to be trainers and advisers who would help that nation resist incursions by Islamic State fighters: "Why did President Obama send troops there? Why did President Trump send troops there? It’s because we sensed that as the physical caliphate is collapsing, the enemy is trying to move somewhere." Mattis added, "We’re trying to build up the internal defenses of another country so they can do this job on their own."