Almost everyone — even many stalwart supporters of the war agaist the Houthi — seem to think that an assault on the Yemeni lifeline port city of Al-Hudaydah, now in its opening stages, is a catastrophic idea. Not only because of UNOCHA’s extraordinary predictions of the likely humantiarian fallout, but also because of its likely impact on UN-backed efforts to reach a political settlement in Yemen, and the possibility that it may instead simply push the Houthis further into their logistical and political embrace (which is real) with Iran.

Unusually, even the UK government — strong supporter of Saudi Arabia’s Yemen policy — has said that UK ministers have being trying to dissuade the Saudi-led coalition. DFID claimed in an email to aid agencies this weekend that “We are doing everything we can through diplomatic channels to discourage an assault on Hodeidah“.

Are they, though? “Everything we can”?

The use of UK-supplied military aircraft and ordnance in Yemen, particuarly by the Royal Saudi Air Force (RSAF), has been much remarked upon. Such remarks are important, but of little immediate help right now: the thing about weapons is that you can’t take them back once you’ve supplied them.

But the UK’s provision of these weapons systems is unusual, because their maintenance, deployment and use by the Saudi Air Force continues to rely on an in-country support programme of several thousand employees of UK companies — both British and non-British nationals. These companies are contracted by the UK MOD, not the Saudi government. Their in-country staff include serving, seconded UK RAF technicians. In short: these support personnel, both civilian and seconded military, are fully under UK MOD control, in both contractual and (sometimes) operational terms. And though since mid-2009 these personnel have been “pulled back” from physically fastening weapons onto aircraft for Yemen sorties, they do almost everything else. They are responsible for maintaining the weapons systems of all Saudi Tornado IDS fighter-bombers — a backbone of the Yemen air war. They work as aircraft armourers and weapons supervisors for the UK-supplied Typhoon fighters deployed at the main operating bases for Saudi Yemen operations, and provide deeper-level maintenance for Yemen-deployed combat aircraft. They “issue” weapons to the aircraft for sorties. The documents and interviews that Katherine Templar and I have gathered over the last 18 months confirms this, as do recent UK ministerial statements.

And, as Joe Lo, Nick Gilby and I recently discovered in the UK’s National Archives, the government-to-government agreement that governs this in-country support — at least for the Tornado fighter-bombers — contains a specific legal “off-switch” for precisely this kind of situation. Article 37 of the second “Al Yamamah” MOU between the UK and Saudi Arabia, which MOD officials have confirmed remains in force, allows the UK government “in the case of the outbreak of war… after consultation with the Saudi Arabian government…[to] suspend the arrangements provided for in the MOU”, removing UK re-supply and in-country support for RSAF’s Tornado fighter-bombers. It’s possible that the other, still secret MOUs governing the Typhoons and other UK-supplied weapons systems may have similar clauses. Certainly in the case of the Tornadoes, the UK government has so far chosen not to activate the clause. Evidently, then, despite their assurances, UK ministers have not done “everything we can“: indeed they’ve declined to use the one clear legal and practical tool they have in their hands that might concretely dissuade or hinder the assault on Al-Hudaydah they claim they want to stop.

Would having this in-country support programme down tools actually stop the assault on Al-Hudaydah? Maybe.

• There’s a ground war too, for which UK support is less integral. But the air war is clearly crucial to this ground offensive.
• There are other nations involved in the Saudi-led Coalition’s air war: but RSAF (together with their UAE counterparts) remain to the fore.
• RSAF have other ground-attack aircraft, particularly US-supplied and US-supported F-15 variants. Nonetheless UK-sustained Tornado IDS fighter-bombers and Typhoon fighters constitute just under 50% of RSAF’s in-service combat aircraft. It’s really no exaggeration to say that the Yemen air war in its current strategic and tactical form couldn’t take place without these UK-supported aircraft and weapons systems.
• Saudi counterparts of the expatriate personnel supporting RSAF could probably keep going for a bit on their own. Though if the private assessments we obtained from officials and technicians at all levels of the support operation are to be believed, this wouldn’t last very long before management, technical and maintenance demands started making some air assets unavailable.
• And, more significantly, the public political signal it would send would outweigh a hundredfold any of the ministerial imploring we’ve been told about over the last few days.

No-one has a true off-switch in a war. But in this specific operation, and this specifical strategic circumstance, this is probably as close as we will ever get.

Of course it’s the nuclear option for UK ministers. The diplomatic fallout would be large, and it might have economic consequences for UK companies and employees too (though Article 37 actually suggests that the Saudi government would be liable for costs incurred for replacing employees withdrawn in the event of armed conflict).

But if ministers really believe, as they’ve said in citing UN estimates, that the assault on Al-Hudaydah “could displace up to 350,000 people and leave hundreds of thousands of Yemenis without access to basic goods, water or healthcare“, and that “any long closure of Hodeidah port is likely to put over 3 million more people at risk of starvation“, then surely if there is ever the time to use the nuclear option of ‘switching off’ RSAF’s UK-supplied weapons, it’s now?

And if they don’t? What does the fact that UK officials have recourse to this clear legal provision, but don’t use it, mean for their potential legal culpability over grave IHL breaches that may be committed in the assault on Al-Hudaydah using weapons systems sustained and supported by UK personnel?

Aiding and abetting grave breaches of IHL has a mens rea test — a threshhold of “knowledge” about the act (though not necessarily intention that it be perpetrated) — that usually makes it unlikely that third-party providers of military assistance, or the government officials responsible for them, could be held individually criminally responsible in such circumstances. But I wonder whether ministers’ very public statements over the last few days about their expectations of a humanitarian catastrophe in the event of an assault on al-Hudaydah might, just might, demonstrate that mens rea test in this case. I’m not a lawyer, and I don’t have the expertise to adjudicate on this question. But if I were Boris Johnson, Teresa May, Alastair Burt, Guto Bebb or any of their ministerial colleagues, I think I’d be quietly consulting m’learned friend right now, just to be sure, about exactly what’s been said, and what’s been done…

(Image by Nicholas Liby, CC BY-ND 2.0)