News stories are now suggesting that the Minnesota stabber Dahir Adan entered the United States as a Somali refugee when he was 2 years old. Ahmad Khan Rahami, the suspected bomber in New York and New Jersey, entered as an Afghan asylum-seeker with his parents when he was 7 years old. The asylum and refugee systems are the bedrocks of the humanitarian immigration system and they are under intense scrutiny already because of fears over Syrian refugees. 

The vetting procedure for refugees, especially Syrians, is necessarily intense because they are overseas while they are being processed. The security protocols have been updated and expanded for them. This security screening should be intense. The process for vetting asylum-seekers, who show up at American ports of entry and ask for asylum based on numerous criteria, is different. Regardless, no vetting system will prevent or detect child asylum-seekers or child refugees from growing up and becoming terrorists any more than a child screening program for U.S.-born children will be able to prevent or detect those among us will grow up to be a terrorist. 

Adan and Rahami didn’t manage to murder anyone due to their incompetence, poor planning, potential mental health issues, luck, armed Americans, and the quick responses by law enforcement. Regardless, some may want to stop all refugees and asylum seekers unless they are 100 percent guaranteed not to be terrorists or to ever become terrorists. Others are more explicit in their calls for a moratorium on all immigration due to terrorism. These folks should know that the precautionary principle is an inappropriate standard for virtually every area of public policy, even refugee screening. 

Even so, these systems are surprisingly safe. According to a new Cato paper, from 1975 to the end of 2015, America allowed in just over 700,000 asylum-seekers and 3.25 million refugees. Four of those asylum-seekers became terrorists and killed four people in attacks on U.S. soil. Twenty of the 3.25 million refugees became terrorists and they killed three Americans on U.S. soil. Neither figure includes refugees or asylum-seekers who traveled overseas to become terrorists abroad as I was solely focused on terrorists targeting the homeland.

The chance of being murdered in a terrorist attack committed by an asylum-seeker was one in 2.73 billion a year. The chance of being murdered in a terrorist attack committed by a refugee is one in 3.64 billion a year. These recent attacks in New York, New Jersey, and Minnesota will make the refugee and asylum programs look more dangerous by increasing the number of terrorists who entered under them. Fortunately, the attackers didn’t kill anybody so the chance of dying in a terrorist attack committed by immigrants who entered in these categories won’t increase – although that is small comfort to the victims who were wounded. 

The terrorism risk posed by refugees and asylum-seekers could skyrocket in the future and justify significant changes in both humanitarian immigration programs, including more intense screening or other actions. The recent attacks in Minnesota, New York, and New Jersey, however, do not justify such drastic changes. 

Correction: An earlier version of this blog reported that the chance of being murdered in a terrorist attack committed by a refugee is one in 3.4 billion a year. That was a typo. The correct figure is one in 3.64 billion a year.