In the wake of the San Bernardino shootings, more Americans than before are trying to grapple with questions about the nature of terrorism, terror activity versus rampage killings, and what can be done to prevent these bloodlettings.

I have been studying these questions for years as part of my self-training. I learned some of the basics of counter-terrorism theory from a former SpecOps officer, and more from my Kung Fu instructor whose day job is as a criminal forensics and counter-terrorism specialist consulting to law enforcement. I’ve also read up on the subject, and thought carefully about what I’ve read.

The following is a primer on how people whose job it is to prevent and mitigate terrorist activity and spree killings think about it.

First I’m going to present a couple of perpetrator types which, between them, account for almost all terrorist acts and rampage killings. Later I’ll point at some edge cases and exceptions.

Our first perpetrator type is what I’ll call a “terror soldier”. This is not a term in use among professionals, I’m presenting it here in order to avoid pre-empting the term “terrorist”.

The terror soldier does not act alone. He has a network behind him; the network provides him with, at minimum, ideological and tactical direction. It may also provide him with safehouses, money, and weapons. Because the terror network has public political objectives, it either has an above-ground political arm or a deniable conduit to a “legitimate” political organization that can operate as its propaganda and recruiting arm.

The opposite archetype is the lone wacko. The lone wacko doesn’t have a network. His motivations are not public and political but personal and, usually, delusional. He is likely to have been a former mental patient, or to have a history that clearly indicates previously undiagnosed mental illness when it is scrutinized after he has gone violent. More often than nor he will have been on long term use of SSRIs (more than five years) or some other prescription antidepressent or antipsychotic medication, and the violent break will be associated with going off or changing his meds.

An important contrasting point about terror soldiers is that they are usually not clinically nuts. Terror networks (like covert operations in general) avoid recruiting mental cases because they’re brittle and unreliable.

A terror soldier has signed up for a bit part in a political war planned by others. A lone wacko is his own reason for slaughter; his motivations are not political but psychological and often inscrutable to anyone outside of his skull.

Generally, when you hear the phrase “terrorism” used to describe a mass shooting or bombing, terror soldiers are at the back of it. Generally, if you hear of a “spree killing” or “rampage killing”, a lone wacko did it. There are some exceptions, which I’ll get to.

These distinctions are important because lone wackos and terror soldiers have different threat profiles. A lone wacko is a tragedy but almost never a disaster; a terror network can scale up violence to much greater levels by deploying multiple soldiers, and is far more likely to have expertise in bomb-making, airplane hijackings, and other means that can inflict casualties well above the level of a rampage shooting with personal firearms.

The difference even has tactical consequences; armed civilian shooters are highly effective at stopping lone wackos, and a major reason is that wackos tend to freeze and surrender when shot back at. This is not the case with terror soldiers.

Thus, if you are a pro, you worry a lot about terror soldiers and much less about lone wackos. The lone wackos are much less dangerous, and (as we’ll see) there’s less you can do against them anyway.

These distinctions are also important because lone wackos and terror soldiers require different counterstrategies. To stop terrorists, you penetrate and destroy their support networks. In fact, you must do this, because unless the network is taken out it will recruit and indoctrinate more soldiers.

Lone wackos can’t be attacked through their networks because they don’t have any. The only way you could stop them is by massively increasing screening for mental illness and getting tough about involuntarily committing the potentially dangerous. In the U.S. the political will to do this has been absent since the de-institutionalization movement of the 1960s; attempts to reverse that would run into both cost problems and serious civil-liberties objections.

The San Bernardino shooters were terror soldiers, not lone wackos. There was more confusion about this than there should have been until Tashfeen Malik’s declaration of allegience to ISIS was discovered. Some people are still confused by the fact that ISIS didn’t provide them material support. But this is exactly what makes ISIS novel and dangerous – it has built a doctrine and toolkit for running soldiers with ideological and tactical direction only, purely through its propaganda arm.

By contrast, the Aurora Theater shooter, James Holmes, was a classic lone wacko. So was Elliot Rodger, the shooter in the 2014 Isla Vista killings. So were Harris and Klebold, the Columbine High School shooters. No network, no ideology, just boiling cauldrons of private hatreds and resentments.

Almost all terrorists or rampage killers fit one of these two profiles. Very occasionally you get some outliers that break the classification. Timothy McVeigh was one – politically motivated, military demolition skills, not mentally unbalanced: every attribute of a terror soldier except the network.

The Unabomber was similar, except borderline crazy. Unlike McVeigh he might not actually be an exception to the usual rules but, rather, best understood as an exceptionally intelligent lone wacko. In the real world, you can never count on category boundaries being perfectly sharp.

One recent borderline case deserves special attention: Dylann Roof, the virulent racist who shot 9 people in a Charleston church in June 2015. Dylann is best understood as a would-be terror soldier who, in contrast to the self-radicalized San Bernardino shooters, failed to find a network to hook up to. There was no ISIS for him; his Facebook stream included complaints that he couldn’t find any racists to hang with.

But I emphasize that Roof and McVeigh and the Unabomber were exceptions; 99% of the time it is very obvious that you are dealing with either a terror soldier (backed by a network) or a lone wacko from just the modus operandi of the killing, and there is almost never any need to change this assessment later.

I’ve been talking as though terror soldiers and lone wackos have roughly the same prevalence, but in fact lone wackos are both less dangerous and far, far more common than terror soldiers – the difference, in the U.S., seems to be roughly an order of magnitude. This has an important consequence; if you’re even a little bit off about distinguishing them, your threat model of the most dangerous bad guys (the terror soldiers) will be badly compromised.

Now I’ll get to the controversial part. A lot of the confusion about terror and rampage killings is politically generated and unnecessary. The operators on the ground are seldom in much doubt about what species they are dealing with, but they’re used to seeing their analyses spun into garble, vagueness, and sometimes outright fabrication by their superiors and the news media.

There are two major reasons for this. One is that for PR reasons, the U.S, government has chosen to underplay the role of Islamist indoctrination in recent terror incidents, implicitly binning terror soldiers as lone wackos. Perhaps the single most egregious example of this was in the 2009 Fort Hood shootings, which the government insisted on publicly categorizing as “workplace violence” despite the fact that the shooter screamed “Allahu akbar!” while firing and the Joint Terrorism Task Force found him to have been communicating with a jihadist imam in Yemen. Co-workers had been aware of the shooter’s increasing radicalization for years.

Another major reason is that the left end of the American political spectrum is heavily invested in the belief that “right-wing terrorism” is prevalent in the U.S. and a greater danger than either left terrorism or Islamism.

This belief is a myth. One recent indicator is the fact that Dylann Roof, a natural hard-right-wing terrorist soldier if there ever was one, never found his network. Another is that anybody can name Islamist terror organizations that operate in the U.S. – ISIS, al-Qaeda – but only specialists know about U.S. incubator networks like The Order and the Christian Identity movement.

In fact, the potentially-terrorist hard right in the U.S. is tiny, isolated, and so incompetent that it can barely find its own ass with both hands, a flashlight, and GPS guidance. It is also heavily infiltrated. (This is not just my opinion, it is what any pro in the field will tell you if you can get them to talk.)

What sustains the myth that right-wing terror is more prevalent than jihadism is, basically, the news media instantly counting any lone wacko with a white skin as a “right-wing terrorist” and sticking to that categorization even when facts contradict it.

This bias is so extreme that Joseph Stack, who flew a light plane into an IRS office in 2010, is still routinely described as “right-wing” even though his suicide note ended by quoting the Communist Manifesto! Another notable example is Jared Lee Loughner, characterized as “right wing” even though his political connections were an incoherent mess of mainly left-wing conspiracy theories and a former classmate testified that he was “left wing, quite liberal” before retreating into private psychosis.

I have to single out for particular opprobrium the Southern Poverty Law Center, an organization that used to do noble work in civil rights but has in recent years been particularly persistent and dishonest in promoting the myth of pervasive right-wing terror. Journalists still treat them as a reliable source, and should not.

Another political hobbyhorse that gets ridden after every mass shooting, whether terrorist incident or rampage killing, is gun control. This article is not really the place to fully analyze the kind of dimwitted magical thinking involved, but I will note one relevant fact: both terror soldiers and rampage killers are known to preferentially seek out posted “gun-free zones” – venues where they are reasonably confident their victims will not be able to shoot back.

Turning away from the politics, ignoring Islamist connections and mis-classifying lone wackos as right-wing terror soldiers are bad things because they distort threat modeling and countermeasures. Reality is what it is. To hold terror and rampage-killing casualties to a minimum you have to face that reality rather than substituting a politically convenient narrative.

A rational strategy for addressing mass killings in the U.S. would include the following elements:

1. Traffic analysis of social-media posts. Terror soldiers leave one distinctive kind of trail, linking to their network. Lone wackos leave another – they tend to be socially isolated by mental illness.

2. Stepped-up efforts to identify violently unstable people and institutionalize them before they flip out. An end to over-prescription of SSRIs and other medications that screw with neurotransmitter balance.

3. More armed civilians and the elimination of “gun-free zones”. (This has been tested and found effective in Israel. In the wake of San Bernardino we are beginning to see police organizations recommend it.)

4. Conventional-force expeditions to recapture or destroy the home grounds of organizations like ISIS and Boko Haram.

These show up repeatedly in every conversation I’ve had with anyone knowledgeable in the field. There may be be good political or ethical reasons for not doing some of them (I’m rather wary of reinstitutionalization, myself), but we must acknowledge that such high-minded restraint will have a cost measured in lost lives.

I will also note some measures which might be effective but are debatable among professionals:

* Tighter border controls. They may work tolerably well in a small, ethnically homogenous country; it is unclear that these can be made long-term effective enough in the U.S. We have porous borders just as a consequence of geography and economics, and a multiethnic population that infiltrators can easily disappear into. On the other hand, not actively pulling in refugees from Syria or other majority-Islamic countries is probably good short-term policy, and there are other good reasons (like the child-rape rates in Rotherham and Malmo) to cut that flow as much as we can.

* Encryption back doors and Patriot-Act-style mass surveillance of content. There are are hot disputes about this. My own judgment is that they are a bad trade-off, or at least that if they are effective the pro-surveillance advocates have dismally failed to produce evidence of same. On the other hand, there are imaginable good reasons for the evidence itself to be suppressed.

I don’t have any neat conclusion to wrap this up with. Or, wait, maybe I do. There’s one other common, major mistake: treating terrorism and rampage killings as crime problems. Neither of them really is.

Rampage killings are a public health problem – police may be the first responders to an incident, but the effective interventions to prevent them them are mainly medical, not criminological.

On the other hand, what terror soldiers do is best thought of as a kind of distributed irregular warfare, intended like all warfare to break the enemy’s will to resist. Criminal enforcement can typically do little or nothing about their networks. Instead, the normal counter to irregular warfare applies; you want to bait them into concentrating so they can be confronted and destroyed by regular forces.

In that respect, ISIS presents an easier target than al-Qaeda did. By proclaiming a caliphate and holding ground, they’ve fixed themselves. It remains to be seen if the West has the political will to actually confront them.