There’s really no way around it: Continuing to admit 1 million Muslim immigrants per decade will translate into more attacks. We need to cut Muslim immigration. But limiting the cuts to Muslim-majority countries would exclude Christians and other non-Muslims and also ignore Muslim immigration from non-Muslim countries such as India, Russia, France, and England.

So alongside ideological screening we need to cut immigration overall, focusing on the categories most likely to cause problems. That means eliminating the visa lottery, an absurd program in its own right but also the source of a disproportionate share of Muslim immigration; limiting family immigration to the closest relations, to prevent a cascading chain of relatives; dramatically curbing refugee resettlement, allowing us to help many more people while keeping the potential security threats off shore; and reducing the number of foreign-student admissions, the feeder program for a large share of new permanent immigration from the Islamic world.

None of these measures is a magic solution. Efforts to screen out Islamic supremacists will often fail. Limiting family migration to spouses would still permit the immigration of people like San Bernardino jihadist Tashfeen Malik. Full assimilation of existing Muslim communities, even if new inflows were reduced to a trickle, would still take time, if it’s possible at all.