Not even a day after Tuesday’s terrorist attack in New York City, politicians had moved on from their statements of “this is a terrible tragedy” to a politicization of the event.

On Twitter, Donald Trump used the attack as an excuse to further his immigration agenda, claiming that the visa lottery system that allowed Sayfullo Saipov to enter our country was to blame for this horrific act of terror, and should thus be eliminated.

He called for a system that vets potential immigrants based solely on merit, doing away with a bill that allows “diversity immigrants” from countries with very low immigration levels to the US to apply to be put into a lottery to receive Visas.

According to the New York Times, Trump is misinformed if he believes this particular bill, passed with support from Democrats and Republicans in 1990, is not merit-based because it requires applicants to have a degree or approved job. Saipov was considered to have the required “merit” to become an American citizen, and was vetted through all the proper channels.

Does this mean we need more stringent vetting processes? Are we letting too many people “slip through the cracks”?

That’s the argument that always emerges after these incidents when they are committed by an immigrant. But it ignores several crucial facts. First, Saipov was “apparently was radicalized after he came to the United States” according to the Washington Post. According to a widely reported assessment by the Department of Homeland Security, radicalization years after arriving to the United States is quite typical of immigrants who commit acts of terror.

So how are we supposed to vet people for terrorism before they have become terrorists? And what about all the American-born citizens who have committed terrorist acts? Should we all have to take mandatory personality tests every month to make sure we haven’t become terrorists?

Because the fact is, many terrorist acts (some have argued that it is the majority), are committed by home-grown Americans.

We already know that any policy by Trump to restrict immigration isn’t based on facts. Earlier this year, it was reported that immigrants from the countries included in his proposed travel ban had literally committed zero terrorist attacks on American soil. But it’s not just Trump.

We as a country have a tendency to revert to nativist ways of thinking when events like this happen. Unlike with school shooters and the like, we never ask questions like “what was the state of his mental health?” or “what was his childhood like?” We definitely don’t ask how the social and cultural norms in our country lead immigrants and native-born citizens alike to commit acts of terror.

What led Saipov to become so obsessed with videos of ISIS on the internet? Why did he become so disillusioned with the country he jumped through hoops to immigrate to seven years ago?

When we ask these questions, we are not excusing the act of terror, but attempting to understand the reasons one becomes a terrorist, beyond them being from a country in the Middle East. And if we look at the why, maybe we can figure out a solution to combating terrorism that doesn’t simply put a rhetorical and nationalistic band-aid on an extremely complex issue.