I’m not certain that that’s legal under the Geneva Convention — oil facilities might well be a military target, but given the context in which Trump is talking, the goal probably isn’t its value as a military target — but then again, Iran hitting Qatari energy facilities is at least as egregious in that degree.

EDIT: I do think that, in general, the laws of war may not have great mechanisms to respond to someone else wiping out civilian infrastructure. Like, setting aside this particular incident, maybe there should be some sort of mechanism added to deal with it.

Ordinarily, you’d think that a country wouldn’t want to spend time destroying civilian infrastructure if it could hit military targets, but in this case, Iran has very limited ability to really attack US or Israeli military targets, but does have the ability to destroy civilian targets in their neighbors. That creates misincentives, I think, and I could certainly imagine similar such situations showing up down the line.

My major concern is that, in the past, there have been cases where attempting to protect civilian infrastructure using deterrence via threatening civilian infrastructure on the other side has resulted in escalation spirals. For example:

https://en.wikipedia.org/wiki/Strategic_bombing_during_World_War_II

On 8 August 1940, the Germans switched to raids on RAF fighter bases.[146] To reduce losses, the Luftwaffe also began to use increasing numbers of bombers at night.[147] From the night of 19/20 August night bombing targeted the aircraft industry, ports, harbours, and other strategic targets in towns and cities, including suburban areas around London.[148] By the last week of August, over half the missions were flown under the cover of dark. On 24 August, several off-course German bombers accidentally bombed central areas of London.[149][150][151] The next day, the RAF bombed Berlin for the first time, targeting Tempelhof airfield and the Siemens factories in Siemenstadt.[152] These attacks were seen by the Germans as indiscriminate due to their inaccuracy, and this infuriated Hitler;[153][154][155] he ordered that the ‘night piracy of the British’ be countered by a concentrated night offensive against the island, and especially London.[156] In a public speech in Berlin on 4 September 1940, Hitler announced that:

The other night the English had bombed Berlin. So be it. But this is a game at which two can play. When the British Air Force drops 2000 or 3000 or 4000 kg of bombs, then we will drop 150 000, 180 000, 230 000, 300 000, 400 000 kg on a single night. When they declare they will attack our cities in great measure, we will eradicate their cities. The hour will come when one of us will break – and it will not be National Socialist Germany!

— Adolf Hitler[157]

The Blitz was underway.[158] Göring – at Kesselring’s urging and with Hitler’s support – turned to a massive assault on the British capital.[37] On 7 September 318 bombers from the whole KG 53 supported by eight other Kampfgruppen, flew almost continuous sorties against London, the dock area which was already in flames from earlier daylight attacks.[156] The attack of 7 September 1940 did not entirely step over the line into a clear terror bombing effort since its primary target was the London docks, but there was clearly an assumed hope of terrorizing the London population.[37] Hitler himself hoped that the bombing of London would terrorize the population into submission. He stated that “If eight million [Londoners] go mad, it might very well turn into a catastrophe!”.

Like, maybe that would have been unavoidable, if Hitler wanted to do it and was looking for any political rationale, but you view it as an escalation spiral where it’s very easy for either side to inadvertently start a raging bonfire, that raises some obvious risks of deterrence via threatening civilian infrastructure. Ideally, whatever structure you have discourages attacks on civilian infrastructure and tends to encourage de-escalation if some does occur.