President Barack Obama's tearful intervention this week in America's gun control debate had an immediate impact. Stocks in arms makers jumped in anticipation of a fresh buying surge by fearful citizens.
Mr Obama would have known this perverse effect was likely. Last month, after the San Bernardino massacre, when an Islamist-inspired husband and wife team killed 22 people in the Californian town, gun and ammunition sales jumped. Such is the climate in gun-saturated America that school classes and workplaces routinely prepare for mass shootings in the way that New Zealand pupils practise earthquake drills.
At town hall meetings police officers deliver lessons in surviving the nightmare of having an "active shooter" in the neighbourhood.
People are encouraged to Google the layout of the local sports stadium before going to a game or concert and to check the exits of the suburban supermarket. Mass shootings occur in the United States about once a month.
Studies indicate some 92 Americans die every day from gun deaths. About a third of these are homicides. A child in America shoots someone on average once a week because guns are so easy to find and fire.
No other developed country comes close to this staggering level of gun violence. Yet the nation pussyfoots around the charged issue of removing from circulation the vast arsenal of military-style weapons and refuses to renew a ban on semi-automatics sales. It is impossible to know the exact number but by some estimates Americans own 300 million guns. Clearly some end up in the hands of deranged individuals.
Guns and the damage they inflict are deeply embedded in American political culture. Four United States presidents have been assassinated - Abraham Lincoln, James A. Garfield, William McKinley and John F. Kennedy. Ronald Reagan survived a round to his chest, and the White House itself has been peppered with gunfire, once when Michelle Obama and daughter Sasha were home.
Mr Obama's latest push into the minefield of gun-control was modest. His executive action expands mandatory background checks to gun shows, flea markets and online sales, adds more than 230 examiners and staff to help process them and calls on states to submit accurate and updated criminal history data.
He wants to make it harder for criminals and dangerous individuals to get hold of weapons.
Those measures are seen as crucial to stemming gun suicides by blocking immediate access to weapons. But even then they would not have kept weapons from the hands of suspects in several of the deadliest recent mass shootings.
Gun control works. Australia bought back semi-automatics from gun owners. Its gun homicide rate is a 20th of America's. In 18 US states where the criminal histories of gun buyers are checked, shooting deaths have fallen significantly. Yet the US Congress, in thrall to the gun lobby, refuses to act. As Mr Obama outlined his gun measures, Republican presidential hopefuls were branding him a wimp and accusing him of behaving like a "petulant child" who wanted to strip citizens of their precious arms.
America seems incapable of a sensible gun control discussion. Mr Obama's tears could be seen against the toll of 225,000 Americans who have died of gun violence during his seven years in office. Americans are easily alarmed by foreign terrorism but the toll guns take from their own armed citizens is much, much worse.