The arithmetic of the strike is the story.

At least five munitions hit Sanaa International Airport on July 13, by Human Rights Watch's count from satellite imagery. Three of them struck the airport's only functioning runway. The stated purpose was to prevent a single aircraft - an Iranian Mahan Air flight - from landing [1].

Three craters in the one runway, to stop one plane.

Sanaa's airport is not an abstraction in Yemen's war. It is the capital's single air connection - the route by which Yemenis with cancer and kidney failure leave for treatment abroad, and by which humanitarian staff rotate.

A closed runway does not inconvenience an air force; the coalition flies from elsewhere. It closes a door civilians use.

HRW's legal language is precise and worth quoting exactly: 'deliberate attacks on objects indispensable to the survival of the civilian population are war crimes' [1].

The organisation attributes the strike to Yemeni government forces operating with the Saudi-led coalition, and it names the purpose - which matters legally, because a runway can be a lawful military objective in some circumstances, and the analysis turns on what the attack was for and what the civilian cost is.

Hours later the Houthis struck Abha International Airport in Saudi Arabia with ballistic missiles and drones, and called it a response [1].

Major-General Turki al-Maliki, the coalition spokesman, called those attacks 'cowardly and reckless' and promised 'necessary operational actions' [2] - each side describing the other's airport strike in the vocabulary it exempts itself from.

One more thing has to be said about the numbers in this theatre, because it shapes everything reported from it: there are no independent casualty counts.

HRW gives none for either airport [1]. For the July 24 strikes on Hodeidah and Kamaran Island, the only count anywhere comes from Houthi-affiliated Al Masirah TV - one woman injured - and the coalition's response was to deny targeting the port while acknowledging strikes in the area [2].

Every number that exists comes from a party to the war.

Afrah al-Zouba, the foreign minister-designate of Yemen's recognised government, framed where this goes: 'The Houthis want to copy the Iranian model, and this will shut down two main straits, the gateways into the Gulf and Red Sea' [3].

Two straits, two airports, and a targeting logic that has stopped distinguishing between what an enemy uses and what a population needs.