Washington Gov. Jay Inslee (D) urged President Donald Trump to drop his idea to arm teachers in the US.

Inslee confronted Trump at a meeting between governors and the president on Monday, arguing that teachers and police don’t actually want what Trump is asking for. Trump in the past week has called to arm a certain percentage of teachers — and paying them “a little bit of a bonus” to do so — to protect students from mass shootings.

“Speaking as a grandfather, speaking as a governor of the state of Washington, I have listened to the people who would be affected by that,” Inslee said. “I have listened to the biology teachers, and they don’t want to do that at any percentage. I have listened to the first-grade teachers, who don’t want to be pistol-packing first-grade teachers. I have listened to law enforcement, who have said they don’t want to have to train teachers as law enforcement agencies, which takes about six months.”

He added, “I just think this is a circumstance where we need to listen — that educators should educate, and they should not be foisted upon this responsibility of packing heat in first-grade classes. Now, I understand you have suggested this, and we suggest things and sometimes then we listen to people about it, and maybe they don’t look so good a little later. So I just suggest we need a little less tweeting, a little more listening.”

Trump did not directly respond to Inslee, instead moving the conversation to other parts of the room.

There is no good research on the effect of arming teachers or the effect of putting more armed police or security in schools — which by itself should raise red flags, given that policy should be evidence-based. But based on the evidence we do have, there’s enough to suggest that putting more guns in schools could actually make gun violence worse.

The fundamental problem in the US is it has a lot of guns, which the research has found closely correlates with higher levels of gun violence. That’s one reason the US, which has the highest levels of civilian gun ownership in the world, also has the highest levels of gun violence anywhere in the developed world.

This is in many ways intuitive: People of every country get into arguments and fights with friends, family, and peers. But in the US, it’s much more likely that someone will get angry during an argument and be able to pull out a gun and kill someone.

On top of that, multiple simulations have demonstrated that most people, if placed in an active shooter situation while armed, will not be able to stop the situation, and may in fact do little more than get themselves killed in the process.

Consider the FBI’s analysis of active shooter scenarios from 2000 to 2013: “Law enforcement suffered casualties in 21 (46.7%) of the 45 incidents where they engaged the shooter to end the threat.” These are people trained to do this kind of thing full time, and nearly half of incidents resulted in at least one officer being wounded or killed. Teachers with limited training would very likely fare much worse.

If America wants to confront its gun violence problem, then, the research suggests it should look to reducing the number of guns in circulation — not putting more armed people in schools.

For more on the case against arming teachers, read Vox’s explainer.