SYMPATHY for President Donald Trump is not commonly expressed in these pages, and the extraordinary and fatal scenes at the funeral of the Iranian general, Qassem Soleimani, on Tuesday are unlikely to increase support for the man who ordered his assassination. Iran has the means of retaliating, as demonstrated on Tuesday night, and a track record of doing so. Anxious US-aligned countries in the region, Israel in particular, are wondering why the Trump administration persists in prodding the Iranian wasps’ nest with a blunt stick rather than subduing it with the smoke of negotiation. It must be acknowledged, however, that modern warfare has few tried and tested rules. The days are long gone when an enemy could be identified by the presence of his army on your border. The sponsorship by Iran of terrorist organisations to act as its proxies has blurred the line between warfare and crime, and the prevention of the latter can excuse a host of measures, including — as was established by previous US administrations — pre-emptive strikes in self-defence against a future attack. There is thus an argument that the killing of General Soleimani prevented further terrorism, while at the same time warning Iran not to support attacks such as those on the Saudi oil refinery at Abqaiq and Khurais last September.

If the old rules cannot be easily applied, there remain helpful guidelines, of which the most obvious is that — whatever principle or moral is involved — an action should not cause more harm than it prevents. Had the Iranian nuclear programme not been frozen by the multilateral deal in 2015, the consequent harm caused by the assassination could have been very grave indeed. As it is, Iran has this week announced the ending of all the restraint in nuclear development. Another guideline is that the benefits of a dubious action should be made quickly transparent. The problem is that President Trump has so undermined his integrity that nothing he now says will be trusted. This is the man whose press secretary said about his utterances last year: “I don’t think they’re lies. . . I think the President communicates in a way that some people, especially the media, aren’t necessarily comfortable with. A lot of the time they take him so literally.” Without a reliable account of the danger posed by General Soleimani, the suspicion remains that his murder was a ploy by a president wishing to distract the US electorate from his impending impeachment.

A final guideline concerns the danger of emulation. A justifiable action can become unjustified if it legitimises similar actions in worse circumstances. Into this category falls President Trump’s Twitter threat against 52 sites “important to Iran and Iranian culture”. For the President even to hint at acts similar to those carried out by IS and the Taliban — in the same week as declaring to supporters “I really do believe we have God on our side” — is to waive any sympathy that might have come his way.