Two announcements marked the end of the Saudi crown prince Mohammed bin Salman’s visit to the UK on Friday. First came a £100m aid deal, promptly branded a “national disgrace”. While DfID says it will pool expertise to boost infrastructure in poor countries, critics say that it is meant to whitewash the reputation of Saudi Arabia, which needs such PR thanks to its leading role in the war in Yemen.

Enter announcement two, from BAE Systems. Saudi Arabia is near a long-delayed deal to buy 48 Typhoon fighters. The country’s military already have 72; some are being used in Yemen. The Campaign Against Arms Trade says the UK has licensed £4.6bn of arms sales to Riyadh since the bombardment began in 2015. Though Theresa May reportedly raised her “deep concerns” about the war with the crown prince, Britain boasts of providing humanitarian aid while supplying the weapons that fuel the world’s worst manmade humanitarian crisis and supporting the Saudi air campaign.

The UN says that 8.5 million Yemenis are at risk of famine. Its humanitarian chief describes conditions as “catastrophic”. The shattered health system battles diphtheria and cholera. The country’s new special envoy, former British diplomat Martin Griffiths, must try to revive the moribund attempts to find a political exit. Whatever the hopes of the Saudi crown prince, there is not a military solution.

The 32-year-old, his country’s de facto leader, has been feted for introducing social and cultural reforms – allowing women to drive, and cinemas to open after a 35-year ban. He is simultaneously consolidating his own power ruthlessly. On the international front, he led the charge into Yemen (and more recently the blockade of Qatar, another reckless initiative which seemed to promise swift victory but is now in stalemate). It is becoming known as “Saudi’s Vietnam”, a tag which Iran has seized with glee. Tehran’s support for the Houthi rebels has baited its great rival into a war which is draining its coffers and costing thousands of Yemeni lives.

The Saudi attempt to find an exit – by persuading Houthi ally and former president Ali Abdullah Saleh to flip – was short lived: the Houthis killed him. The internationally recognised president is Abdu Rabbu Mansour Hadi, who succeeded Saleh in the Arab spring, only to be forced out by the Houthis. But his government has little actual presence. As a recent report warned, Yemen has become a “chaos state” in which “each territory has its own leadership structure, internal politics, and external backers ... less a divided country than a collection of mini-states engaged in a complex intraregional conflict”. The “Yemen National Army” is really a loose anti-Houthi coalition of Sunni Islamists, southern secessionists, northern tribesmen and others. Many of those elements have made political and territorial strides thanks to the conflict, and are filling their pockets thanks to the flourishing war economy. Both domestic and international players have a lot at stake.

A successful peace initiative will need to involve them all, as complex as that will be; a simple deal bearing no relation to realities cannot hold. It will also require persuading Riyadh to be clearer and more realistic about its aims. Britain’s shameful role in Yemen gives it an extra duty to press that case. But for now it seems more focused on security and promoting Typhoon sales.