How grimly galling, as Donald Trump ostentatiously marks today’s 75th anniversary of one of the world’s biggest battles, that he is so ready to risk starting another one of potentially greater magnitude. What could possibly be that dangerous, you might ask. Answer: selling American nuclear knowhow to Saudi Arabia without radiation-proof guarantees that it will not be used to make atomic bombs.

Belated confirmation came this week that the US department of energy has issued seven separate permits to allow transfers of nuclear technology to Riyadh. Belated, because the information was purposefully withheld until Democrats insisted on seeing it. Belated also because Trump, his family and associates are doubtless aware of suspicions that they could benefit financially from these or future sales.

The fact that two licences were issued after last autumn’s murder of the US-based Saudi journalist, Jamal Khashoggi, is not the worst of it. Rather than punish the Saudi regime for the killing, as decency and the facts demanded, Trump went ahead regardless. Nor is another noxious fact – that the Saudis are prosecuting a merciless war against the people of Yemen – the single most powerful reason for objecting.

More terrible than any of that is the blindingly obvious danger that providing nuclear expertise to Riyadh will push Iran, their sworn enemy and regional rival, into developing its own nuclear capabilities. Supposedly the whole point of Trump’s campaign of threats and sanctions is to deter Tehran from doing just that. To provoke Iran in this fashion is astonishingly stupid – and hypocritical.

It is simply not good enough to say that two planned Saudi reactors, for which multibillion dollar tenders will be sought next year, are intended for civilian, not military use. So far at least, Riyadh has reportedly refused to offer standard guarantees that it will eschew uranium enrichment and plutonium reprocessing, two well-worn pathways to nuclear weapons, or accept independent inspections.

Senator Tim Kaine: ‘I have serious questions about whether any decisions on nuclear transfers were made based on the Trump family’s financial ties rather than the interests of the American people.’ Photograph: Andrew Harnik/AP

Since it signed a UN-endorsed agreement in 2015 to curb its nuclear-related activities, Iran is said to have abided by its terms, including allowing anytime, anywhere inspections by the International Atomic Energy Agency. Full cooperation may soon end, due to Trump’s daft decision to renege on the pact. Yet the escalatory prospect of a Saudi A-bomb could propel Iran into an all-out, headlong race to arm itself.

Nor is it good enough to say, like Rick Perry, Trump’s energy secretary, that if Washington does not give the Saudis what they want, others will. This is a hackneyed, age-old argument used by gun-runners the world over. Perry has claimed that China and Russia do not give a “tinker’s damn” about non-proliferation. Even if that were true, is he really suggesting that the US can or should ignore its own rules and those of the UN and nuclear allies such as Britain and France?

Congressional critics suspect the White House is using one-off licence approvals to surreptitiously bypass the so-called “123” safeguarding process. They also point to connections between the Trump clan and the Saudis. “I have serious questions about whether any decisions on nuclear transfers were made based on the Trump family’s financial ties rather than the interests of the American people,” said Democratic senator Tim Kaine.

If all this were not enough to convince any sensible person that Trump’s Saudi sale-of-the-century is a thoroughly irresponsible idea, consider this: Mohammed bin Salman, the hotheaded Saudi crown prince, vowed last year that if Iran developed a nuclear bomb, “we will follow suit as soon as possible”. Since Saudi and Israeli officials maintain that Iran is already doing exactly that, the implication is clear.

Saudi journalist Jamal Khashoggi was murdered at the Saudi consulate in Istanbul on 2 October 2018. Photograph: Hasan Jamali/AP

The burgeoning nuclear deal is of a piece with Trump’s wider Saudi sycophancy and, in part, is payback for Riyadh’s help in keeping world oil prices low. Another product of this toxic relationship is Trump’s recent overturning of a congressional ban on conventional arms sales. The ban reflected broad concerns about Yemen but also about the autocratic regime’s unsubtle interventions in Libya and Sudan, its persecution of women’s rights activists, and the unresolved Khashoggi affair. Evidently, such concerns are not shared in the Oval office.

Trump and the Saudis is a bad combination. Trump and nukes is even worse. At his behest, key nuclear arms control treaties, like the INF pact with Russia, have been torn up on a whim or, like New Start, will simply be allowed to lapse. As next year’s review conference of the landmark 1968 Nuclear Non-Proliferation Treaty approaches, the US is merely offering more talks about talks, rather than a commitment to finally honour the treaty’s dog-eared promise of nuclear disarmament.

Trump claims he wants rid of nuclear weapons. But this is double-speak from a notoriously two-faced man. The global non-proliferation consensus is unravelling; just look at North Korea. The US, like Russia and China, is modernising its existing nuclear arsenal and seeking new weapons. Others may follow suit. And as his shady Saudi deals show, Trump would rather make a killing – no matter who gets killed.

• Simon Tisdall is a foreign affairs commentator