The United States can't say with precision how many terrorists exist in the world. There are a lot of reasons for this, including that most terrorists operate in secret and including the nebulous boundaries of the word itself. (Which is to say: How one defines "terrorist" can vary.)
What seems clear, though, is that, to the best of our knowledge, Sen. Ted Cruz's statement about terrorists during Thursday night's Republican debate is likely without basis.
Cruz was responding to Donald Trump's also-nebulous explanation of how he planned to fight terrorism were he elected president. Cruz dismissed Trump's ideas, saying, "You've got to understand the nature of the threats we're facing and how you deal with them. And yes, it is true there are millions of radical Islamic terrorists who seek to kill us. We need a president, commander in chief focused on fighting them."
That's the problem. It's not clear that this is true.
The State Department collects data on foreign terrorist organizations, including many you've heard of and many you haven't. A list of the organizations is at the bottom of this article, along with estimates of their size (from the State Department or other organizations) and whether or not they are Islamic. (For their purposes, State isolates organizations that are a threat to American nationals or security.)
If we look at the organizations for which the State Department estimated sizes, we can get an estimate of total size. If we assign a large estimate for organizations for which State doesn't know size, the figures are slightly larger.
(Quick note: This uses a figure of 300 for strengths identified as "hundreds" and 3,000 for "thousands." If a strength range was given, the figure used is the upper limit. For organizations with "unknown" strength, each was assigned a strength of 1,000 members for the bottom bar graph.)
A high estimate, then, is that there are 132,000 members of Islamic terror organizations around the world. This includes al-Qaeda and the Islamic State, which number in the tens of thousands. The total is a lot — but it's not millions.
This excludes radicalized individuals and people within the United States, like the shooters in the attacks in San Bernardino. But here we step back into murkiness. Is someone who would like to do harm to an American a "radical Islamic terrorist," in Cruz's definition. In 2014, there were 13,463 terrorist attacks across the world, according to the State Department, most in the Middle East. The perpetrators of those attacks, aligned with the organizations below or not, are clearly terrorists. But beyond that, it's hard to pin this down.
There have been surveys, including from Pew Research, suggesting that a percentage of Muslims, varying by nation, see violence as often or sometimes justified to defend Islam. The averages by country hover around 10 percent -- but it is too much of a stretch to call those sympathetic to terror tactics "radical Islamic terrorists," just as it is a stretch to say that supporters of any particular thing are themselves that thing.
What Cruz suggests is that there are at least 13 radical Islamic terrorists operating as individuals out in the world for every one affiliated with one of the terror organizations below — most of whom have never committed an act of terror. Cruz has an incentive to overestimate the figure: the argument that President Obama has failed in the battle against Islamist terror is central to Cruz's critiques of the administration.
The word "terrorist" can be surprisingly hard to apply. But it's also hard to see how Cruz's estimate could be correct.
Terror groups identified by the State Department at the end of 2014
Abdallah Azzam Brigades. Islamic. Unknown membership.
Abu Nidal Organization. Islamic. Unknown membership.
Abu Sayyaf Group. Islamic. Up to 400 members.
Al-Aqsa Martyrs Brigade. Islamic. Up to 300 members.
Ansar Al-Dine. Islamic. Unknown membership.
Ansar Al-Islam. Islamic. Unknown membership.
Ansar Al-Shari'a in Benghazi. Islamic. Unknown membership.
Ansar Al-Shari'a in Darnah. Islamic. Unknown membership.
Ansar Al-Shari'a in Tunisia. Islamic. Unknown membership.
Ansar Bayt Al-Maqdis. Islamic. Up to 300 members.
Army of Islam. Islamic. Up to 300 members.
Asbat Al-Ansar. Islamic. Up to 650 members.
Aum Shinrikyo. Up to 1800 members.
Basque Fatherland And Liberty. Up to 450 members.
Boko Haram. Islamic. Up to 3,000 members.
Communist Party of Philippines/New People's Army. Up to 4,000 members.
Continuity Irish Republican Army. Up to 50 members.
Gama'a Al-Islamiyya. Islamic. Up to 1,000 members.
Hamas. Islamic. Up to 3,000 members.
Haqqani Network. Islamic. Up to 300 members.
Harakat-Ul Jihad Islami. Islamic. Up to 300 members.
Harakat Ul-Jihad-I-Islami/Bangladesh. Islamic. Up to 500 members.
Harakat Ul-Mujahideen. Islamic. Up to 300 members.
Hizballah. Islamic. Up to 3,0000 members.
Indian Mujahedeen. Islamic. Unknown membership.
Islamic Jihad Union. Islamic. Up to 200 members.
Islamic Movement Of Uzbekistan. Islamic. Up to 300 members.
Islamic State in Iraq and the Levant. Islamic. Up to 31,500 members.
Jama'atu Ansarul Muslimina Fi Biladis-Sudan (Ansaru). Islamic. Up to 1,000 members.
Jaish-e-Mohammed. Islamic. Up to 300 members.
Jemaah Anshorut Tauhid. Islamic. Up to 3,000 members.
Jemaah Islamiya. Islamic. Up to 3,000 members.
Jundallah. Islamic. Unknown membership.
Kahane Chai. Up to 100 members.
Kata'ib Hizballah. Islamic. Up to 400 members.
Kurdistan Workers' Party. Islamic. Up to 5,000 members.
Lashkar e-Tayyiba. Islamic. Up to 3,000 members.
Lashkar i Jhangvi. Islamic. Up to 300 members.
Liberation Tigers of Tamil Eelam. Unknown membership, but perhaps 15,000 or so.
Libyan Islamic Fighting Group. Islamic. Unknown membership.
Mujahidin Shura Council in the Environs of Jerusalem. Islamic. Up to 300 members.
Al-Mulathamun Battalion. Islamic. Unknown membership.
National Liberation Army. Up to 2,000 members.
Palestine Islamic Jihad - Shaqaqi Faction. Islamic. Up to 1,000 members.
Palestine Liberation Front - Abu Abbas Faction. Islamic. Up to 500 members.
Popular Front for the Liberation of Palestine. Islamic. Unknown membership.
Popular Front for the Liberation of Palestine-General Command. Islamic. Up to 300 members.
Al-Nusrah Front. Islamic. Up to 3,000 members.
Al-Qa'ida. Islamic. Perhaps tens of thousands, though the membership is hard to determine.
Al-Qa'ida in the Arabian Peninsula. Islamic. Up to 1,000 members.
Al-Qa'ida in the Islamic Maghreb. Islamic. Up to 500 members.
Real Ira. Up to 100 members.
Revolutionary Armed Forces Of Colombia. Up to 9,000 members.
Revolutionary Organization 17 November. Unknown membership.
Revolutionary People's Liberation Party/Front. Up to 100 members.
Revolutionary Struggle. Unknown membership.
Al-Shabaab. Islamic. Up to 3,000 members.
Shining Path. Up to 100 members.
Tehrik-e Taliban Pakistan. Islamic. Up to 3,000 members.