The issue of so-called recalcitrant countries has traditionally been handled by the National Security Council, in part because it overlaps with sensitive foreign relations matters, such as fighting terrorism — and Miller is not a part of the NSC.

But, Miller, who recently turned 33, led several of the meetings. And he would launch the sessions with horror stories about Americans being victimized by noncitizens, such as a 25-year-old Connecticut woman stabbed to death by a Haitian man who should have been deported earlier. The tone left some in the room feeling anxious about trying to argue against him, according to current and former U.S. officials.

“‘What are we doing to save American lives? We must save American lives! We must save Americans from these immigrant criminals!’” a former NSC official recalled Miller saying in one session. “He would tell these stories to make it clear there was no room for anything other than to come down hard on these countries, even if we had other national security interests to consider.”