EVERYBODY says that they deplore violence. Yet somehow the John Wick trilogy of action movies, notching up 377 grisly deaths, has taken more than half a billion dollars at the box office. Perhaps that’s just how we indulge an evolutionary urge towards violence harmlessly through fiction.

Most of the world’s leading religious and philosophical theories roundly condemn violence, too, though the record of their adherents shows that practice and theory are divergent, to say the least.

In political theory, however, notably in Machiavelli and Hobbes, the focus is not on an idealised rejection of violence, but about how its use can be constrained and harnessed (with reduction a side issue).

The sociologist Max Weber went as far as maintaining that the primary definition of a state was that it reserved to itself a monopoly on violence – the opposite of the enlightenment idea that citizens lend the state coercive powers, but perhaps one that seems, like it or not, more in tune with the world we live in.

The oldest political act of all is assassination. Yet despite its continual deployment by all cultures, the usual political response to it has, until very recently, been not only to condemn, but to deny it as a practice.

The example of Julius Caesar – where none of the conspirators came to power, and all were dead within a few years – may be one reason politicians are suspicious of its utility; a more obvious one is that any political leader is a potential target.

Very few people have mounted a moral defence of assassination. The closest would have been a claim of utility – that killing, say, Hitler, might have prevented millions of deaths in war. As with all counterfactuals, no one knows whether that would have been true.

Since Hitler’s death, the number of wars, the total killed in them, the number killed in battle and even the number of violent crimes has been declining sharply around the world – despite obvious and horrific atrocities in Rwanda, Bosnia, Syria and elsewhere.

Partly that must be because none of the “Great Powers” has been overtly at war with one of the others for five decades, so conflicts are generally on a smaller, localised, scale.

Even in those, fewer people are being killed. The figures remain awful: 29,499 people, two-thirds of them civilians, were killed last year by explosive weapons alone. But conflict, however horrific, is becoming more selective.

And consequently, more blatant about assassination. No one doubts that the US, under most presidents, always attempted killings of its enemies, but under Ford, Carter and Reagan, Executive Orders prohibited assassination as a policy.

President Clinton was the first openly to advocate targeted strikes (against Osama bin Laden, amongst others). George W Bush’s spokesman encouraged the assassination of Saddam Hussein in 2002. Barack Obama was quite open – indeed, proud – when US forces finally got rid of bin Laden, as was Donald Trump when the ISIS leader Abu al-Baghdadi was killed.

The differing reaction to the death of the Iranian general Qasem Soleimani cannot be because the ethical considerations are different. Assassination is either acceptable or not. If, in certain circumstances, it is (America’s view under recent administrations, which all considered killing Soleimani), he was as well-qualified as bin Laden, both on his atrocities and as an enemy of the US. No one disputes that he was responsible for thousands of deaths, war crimes and terrorist attacks.

The only explanation for the different reaction is that, by dint of his political position, he was protected from direct attempts on his person: because any regime’s officials (no matter how wicked) enjoy a kind of diplomatic immunity except in time of war, or for the connected reason that the consequences have not been considered, so it could be dangerous or counterproductive to kill them.

From what we know of Mr Trump, it seems perfectly likely that he has not thought it through. But since we’re dealing with Realpolitik rather than morality, the USA has a good case for claiming that this was not a provocation, but a reaction.

This may have been Iran’s second-most powerful man, but he was acting, in other territories, as a terrorist. The US embassy had just been attacked, and sprayed with the Arabic graffiti equivalent of “Soleimani was here”. Then Ayatollah Khamenei, calling the US President “this guy” on Twitter, taunted him with the words: “You can’t do anything”.

You don’t need to be a fan of Mr Trump’s to see this as the kind of provocation the US doesn’t normally accept. Violence may not be good. But if America does kill its enemies, he was a good candidate. Whether it was a good move politically remains to be seen.