This week, President Trump accused 75-year-old protester Martin Gugino — currently hospitalized after Buffalo police officers knocked him down — of being an “ANTIFA provocateur.”

Antifa is short for anti-fascist. It’s a loosely organized anti-racist movement that Trump has blamed for violence at recent protests. (Justice Department cases related to the protests thus far do not show links to antifa.) Last week he announced he would designate antifa a “terrorist organization.”

What does it mean to ‘designate’ something a terrorist group?

The federal government usually uses the term “designate” for officially assigning a group to the foreign terrorist organization (FTO) list, as enabled by Section 219 of the Immigration and Nationality Act. The State Department, in coordination with other stakeholders, decides which groups get designated. As its name implies, the list only contains groups foreign to the United States, such as Abu Sayyaf Group, which operates in the Philippines, and Boko Haram, based in Nigeria. Thus, by definition, antifa, or at least the U.S. antifa, cannot be on this list.

However, aside from that list, the State Department or Treasury Department can designate other foreign entities as terrorists, such as the Russian Imperial Movement, under Executive Order 13224. Designation as an FTO requires U.S. financial institutions to freeze the designated groups’ assets and it makes it illegal for Americans to provide “material support” to the groups. Under these two methods combined, the federal government has designated dozens of groups around the world as terrorists, although scholars debate whether these sanctions have much effect.

The United States has no comparable domestic terrorism statute, although some observers suggest that Congress should pass one. There is no U.S. government list of domestic terrorist groups.

So it’s not clear what Trump means by promising to designate antifa as a terrorist group.

Is antifa an organization?

Antifa seems to be more of a social movement than a traditional organization. There are some local clusters, some semi-organized local committees, but no single formal organization that governs activists’ membership, ideology or behavior.

Actual terrorist organizations such as the Islamic State have job applications that potential members must fill out — indicating their skills, background and so forth. Applicants are screened and, if accepted, trained. Other groups, such as the Provisional Irish Republican Army, have done the same. These groups have leaders, ranks and rules.

It’s unlikely antifa has anywhere near this level of bureaucratization. Any anti-fascists willing to engage in violence would probably avoid organizing themselves in a serious manner — realizing how easily law enforcement could infiltrate such a group. In the United States, with its extreme surveillance capabilities including such features as monitoring phones and deploying undercover agents, activists and extremists more commonly rely on what’s called “leaderless resistance.”

This question of whether antifa is an organization is important: Enforcing a ban on a group requires that such a group exists.

If not, who are the members? Is someone who writes “antifa” on their backpack a member? Is anyone who says they are anti-fascist a member? Could someone get in trouble for liking one of the many antifa Facebook pages? Trying to enforce any punishment of group membership would quickly run afoul of constitutional guarantees of freedom of speech.

Has antifa used terrorism?

That may be a moot question, since antifa doesn’t appear to be a single organization. A more useful question might be: Have individuals carried out acts of terrorism in antifa’s name?

However, that immediately brings us to the next question: What exactly is terrorism? Scholars, policymakers and observers heatedly debate that definition. One U.S. government definition of terrorism is “premeditated, politically motivated violence perpetrated against noncombatant targets by subnational groups or clandestine agents.”

Under this broad definition, an act such as punching a Nazi (if he or she is a “noncombatant”) or beating up a journalist could be considered terrorism. But this is probably not what most people think of when they think of terrorism. Assaulting a police officer could be political as well, although law enforcement would probably respond to this as a serious criminal act.

Vandalism — breaking windows, for example — might not be violent enough to be considered the violence of terrorism. (A U.S. government definition of domestic terrorism requires it to “dangerous to human life.”) Much of the crime associated with antifa at protests is vandalism.

These actions contrast with some other U.S.-based groups, such as Atomwaffen Division, whose members are accused of murder and plotting mass attacks. The president has not suggested a terrorist label for Atomwaffen Division.

Was he serious? And what’s next?

It’s hard to know if the president actually plans to try to designate antifa with terrorist status. The tweet could have been an effort to suggest that he is doing something about the fringe violence that came after some of the early Floyd protests, or it could be a way to agitate his followers.

This is not the first time he has made such a suggestion. In August of last year, he also said he might label antifa a terrorist organization. He also claimed that he would designate Mexican drug cartels as foreign terrorist organizations. This might be legally more feasible than designating antifa, given that the cartels are indeed both foreign and organizations. But he never followed through.

However, Trump may have asked the Justice Department to focus law enforcement attention on the group. That would be consistent with reports that the FBI and other security agencies are trying to infiltrate the movement.

The Trump administration is unlikely to designate antifa a terrorist group in counterterrorism law. If it did, that designation would be difficult to enforce, since antifa is not really an organization. Nor is it clear how much antifa supporters have committed actual terrorism. But Trump’s announcement could suggest that U.S. counterterrorism agencies are shifting their priorities. This is worth watching.

Brian J. Phillips (@brian_jphillips) is a senior lecturer in the department of government at the University of Essex and an affiliated professor at the Centro de Investigación y Docencia Económicas (CIDE) in Mexico City.