Wars are paid for twice: first in blood, then at the till. Seven months into the American-Israeli war on Iran, the bill is arriving across the region — in Baghdad, where oil revenues are sagging; on Yemen’s Red Sea coast, where Houthi rebels are advancing; and at the United Nations, where Pakistan’s prime minister has drawn a line in the sand around Islam’s holiest cities.

Iraq’s predicament is the most strictly economic, and the most ironic. The country is a one-crop economy: it imports nearly everything, from food and medicines to appliances and industrial raw materials, and pays for it all with crude. Until recently the sums worked — oil sales comfortably covered the import bill and left a trade surplus. That arithmetic held only while tankers moved freely through the Strait of Hormuz, the throat of the country’s trade with the world.

Since the war began in late February, the free flow of trade through the strait has ended — a closure whose diplomatic endgame remains unresolved. Exports are disrupted, imports have grown costlier and the dinar has weakened. Iraq’s prime minister, Ali al-Zaidi, now describes his country as “facing extraordinary economic challenges”. Few states have built their prosperity on a narrower chokepoint; fewer still have had that chokepoint closed by somebody else’s war.

Yemen comes in from the cold, briefly

Yemen’s own war, older and crueler, has been reshuffled by the regional convulsion. Rashad al-Alimi, chairman of the internationally recognised Presidential Leadership Council, used a speech on Friday — his first since government forces were routed from the western Red Sea coast — to urge Yemenis to mobilise and join the Saudi-backed armed forces. The immediate worry is the Houthi advance towards the Bab al-Mandeb strait, the gateway between the Red Sea and the Gulf of Aden. Mr al-Alimi also pledged to pardon any Houthi fighter who defects to the government side, an amnesty born of necessity rather than magnanimity.

The Houthis’ reach is what concentrates minds far beyond Sana’a. Addressing the UN General Assembly in New York on Friday, Pakistan’s prime minister, Shehbaz Sharif, condemned recent Houthi attacks on Saudi Arabia as “deplorable” and warned that any “threat to the sanctity” of Mecca and Medina would be a “red line that must never be crossed”. His remarks came as the army chiefs of Pakistan, Saudi Arabia and Turkey met to discuss a “Mecca pact” and closer military ties — a conversation that not long ago would have seemed improbable.

As ever in Yemen, the abstraction of chokepoints and red lines dissolves into misery on the ground. The UN children’s agency said on Friday that fighting is disrupting access to healthcare and treatment centres, driving a rise in acute malnutrition. More than a quarter of the nearly 2,900 children screened by UNICEF in recent weeks were acutely malnourished, Akhil Iyer, the agency’s country representative, told reporters in Geneva, as violence escalates across the country.

The connective tissue of these four dispatches is water — or rather, water as a weapon and vulnerability. Close one strait and Iraq’s surplus evaporates; threaten another and Yemen’s ragged ceasefire logic collapses into fresh mobilisation, defectors’ amnesties and hungry children. Wars between great powers and their proxies are often described in terms of deterrence and escalation. The region’s accountants and paediatricians could offer a more accurate vocabulary.

What happens next depends on whether the straits reopen and whether the Houthis press their advantage on the coast. Pakistan’s red line suggests the price of further expansion may rise; Iraq’s dwindling revenues suggest the cost of the status quo is already being paid, by a country that started none of it.