“It is quite telling that this administration — which seems to have unlimited resources to circumvent our immigration laws and further its executive amnesties — cannot find the time or resources to provide timely answers to these simple questions,” Sessions and Cruz wrote.

In November 2015, in a letter co-signed by Texas Sen. Ted Cruz, then-Alabama Sen. Sessions accused the Obama administration of refusing to provide immigration information about defendants who had been charged in U.S. District Court with international terrorism-related offenses.

While the Trump administration has struggled to provide evidence to support the need for a travel ban targeting Muslims, Attorney General Jeff Sessions has been working since at least 2015 to limit Muslim immigration.

So the two senators took matters into their own hands. Using a list of 580 terrorism-related defendants provided by the Justice Department, Sessions assigned the staff of the Subcommittee on Immigration and the National Interest, which he chaired at the time, to research the country of origin and immigration status of each defendant. The committee staff found that of the 580 terrorism defendants they researched, 375 were born outside the United States. To Sessions and Cruz, this validated their view that terrorism was a largely foreign threat.

In another letter to the Obama administration in June 2016, Sessions and Cruz wrote that the information “makes clear that the United States lacks the ability to properly screen individuals prior to their arrival to the United States. It further makes clear that our nation has a serious assimilation problem.”

The Sessions data, which included country of origin and immigration data for some, but not all, of the defendants, was among the sources used by The Intercept to build a database of international terrorism prosecutions since the 9/11 attacks. (The Intercept intends to keep the database up to date and expand the fields regularly; at present, staff members are researching, among other data, the country of origin for approximately 350 international terrorism-related defendants not found by the subcommittee staff.)

A review of the Sessions data, however, suggests that neither country of origin nor immigration status is a clear indicator of heightened national security concern.

COUNTRY OF ORIGIN NUMBER OF PEOPLE United States 73 Pakistan 61 Lebanon 27 Somalia 21 Colombia 20 Yemen 20 Iraq 19 Egypt 17 Jordan 16 Afghanistan 10 Palestine 9 Saudi Arabia 9 India 8 Gaza 7 Syria 7 Morocco 6 West Bank 6 Indonesia 5 Kuwait 5 Canada 4 El Salvador 4 Iran 4 Turkey 4 United Kingdom 4 Albania 3 Bangladesh 3 Guyana 3 Mali 3 Sri Lanka 3 Sudan 3 Tunisia 3 Algeria 2 Bosnia 2 Eritrea 2 Ethiopia 2 France 2 Haiti 2 Kazakhstan 2 Kosovo 2 Libya 2 Nigeria 2 Senegal 2 Singapore 2 South Africa 2 Tanzania 2 Venezuela 2 Angola 1 Australia 1 Brazil 1 Cambodia 1 Chile 1 Denmark 1 Djibouti 1 Dominican Republic 1 Germany 1 Greece 1 Guatemala 1 Israel 1 Ivory Coast 1 Kuwait – Citizen of Jordan 1 Lebanon – Canada 1 Malaysia 1 Mexico 1 Nicaragua 1 Pakistan – Canada 1 Panama 1 Paraguay 1 Peru 1 Philippines 1 Qatar 1 Russia 1 South Korea 1 Trinidad & Tobago 1 United Kingdom – India 1 Uzbekistan 1 Vietnam 1 Yugoslavia 1

While at first blush the Sessions data may seem to suggest disproportionate numbers of terrorism defendants from countries affected by the travel ban, or by immigrants who came to the United States as refugees, the data is incomplete — country of origin is not known for 132 defendants, or 23 percent — and inherently biased by prosecutorial targeting. Following the 9/11 attacks, with the FBI increasing its number of informants in Muslim communities due to a presidential mandate, Muslims became the primary focus of terrorism investigations and, by extension, prosecutions for charges related to international terrorism. Many of these prosecutions were not for serious offenses such as material support or weapons of mass destruction, but instead for nonviolent crimes such as immigration violations or lying to FBI agents.

In addition, the U.S. government segregates terrorism prosecutions into two types — domestic and international. The Sessions data includes only prosecutions related to international terrorism and leaves out all prosecutions of domestic terrorists, who are in most cases born in the United States.

Of the 580 defendants in the list, Sessions’s committee staff found the country of birth for 448 based on open-source research. Of those, U.S.-born American citizens represented the single largest group, with 73 defendants. The second largest group, consisting of 61 defendants, was from Pakistan, which is not affected by the travel ban.

The numbers fall precipitously from there. The third-largest group, consisting of 21 defendants, was from Somalia, which is included in the travel ban. The other countries included in Trump’s travel ban were Iran (four), Libya (two), Sudan (three), Syria (seven), and Yemen (20). Iraq, which was in the first version of the travel ban but not the second, had 19 terrorism defendants in Sessions’s data.

For comparison, 20 of the terrorism defendants in the Sessions data were born in Colombia, the same number of defendants who were born in Yemen. If the travel ban were indeed about restricting travel from terror-prone nations, as the Trump administration has claimed, the Sessions data would in theory provide a compelling case for adding Colombia, a Catholic-majority nation, to the ban list.

The Trump administration’s travel ban, which was established by executive order and affected seven Muslim-majority nations in its first iteration and six in its second, also temporarily blocks refugees from entering the country. Of the 448 defendants for whom Sessions’s committee staffers could find information, 24 entered the United States as refugees. According to the Sessions data, not a single refugee from Syria has been charged with terrorism-related offenses in the United States. Trump’s first travel ban blocked Syrian refugees indefinitely. The current travel ban places a temporary halt on the entry of all refugees.

Neither version of Trump’s travel ban is in effect, following multiple successful court challenges arguing that the executive orders discriminate against Muslims. The Trump administration has filed notice to appeal at least one ruling that halted the second version of the travel ban.