LaPierre’s call was echoed by a group that may never have previously agreed with him on anything. Even before he spoke, left-wing activist group MoveOn.org was circulating a petition for federal lawmakers to implement the same idea following the Dec. 14 attack, in which 20 first-graders and six adults were gunned down in an elementary school in an affluent and bucolic New England town an hour north of New York.

Law enforcement experts are divided on the idea, with some saying no price is too high in the wake of the Connecticut horror and others saying it would be a rash overreaction and that the decision to deploy police officers is best left to local professionals.

There are about 100,000 public schools in the U.S. Assuming an average annual salary of $50,000 for each police officer, the cost of stationing a cop in every school would be somewhere around $5 billion. That wouldn’t include pension and benefits, but it also would not take into account schools that already host police officers or jurisdictions where schools might be covered with no additional hiring.