The campaign by the Trump administration against the World Health Organization has often seemed faintly preposterous.

Over the months of the coronavirus pandemic its untruths and hyperbole have been dismissed by many as iterations of Trumpspeak, whose main purpose has been to distract from the US’s catastrophic response to Covid-19, which has claimed almost 140,000 lives and devastated the economy.

In recent weeks, however, the actions of the Trump administration have moved from dodgy dossiers and fake claims to a far more sinister agenda, and one with real world consequences that may result in more lives lost, not least in the developing world.

After announcing the withdrawal of the US from the WHO, secretary of state Mike Pompeo has levelled an extraordinary series of accusations against the global health body’s head, Tedros Adhanom Ghebreyesus, denouncing him to a private meeting of British MPs as essentially an agent of Beijing and suggesting the WHO was responsible for British deaths.

Coming hard on the heels of the Trump administration’s successful pressure to push the Chinese firm Huawei out of this country’s 5G network, the suspicion must be that the US is now lobbying for support from the UK for its destructive line against the UN health body.

This matters for multiple reasons. The WHO – bureaucratic, inefficient and slow-moving as it can be – serves a fundamental purpose as the primary clearing house on health issues worldwide, including communicable and non-communicable diseases, acting as the first line of defence in serious disease outbreaks such as the current pandemic.

It works for global reproductive health and rights, for the eradication of preventable childhood diseases such as measles, and in the struggle against some of the world’s biggest killers, such as malaria, as well as in health education.

None of which you would recognise from Pompeo’s characterisation of the body as some kind of covert Chinese-influenced stooge.

Increasingly one is forced to wonder whether the animus aimed by Trump at the Ethiopian Tedros – in keeping with the long history of attacks on Barack Obama – is as much to do with the colour of his skin as his expertise.

On one level, the attacks reflect the denigration of science and expertise that has long been a hallmark of Trump and his senior officials, aimed too at public health experts like Anthony Fauci.

All of which has more significance coming from one of the world’s leading nations, setting a tone for populists elsewhere.

Perhaps that should not be surprising given Trump’s own largely unthinking history on public health that has seen him swerve from an anti-vax position to his clumsy attempt to scoop up potential Covid-19 vaccines and treatments for US use.

On a more practical level, the US withdrawal from the UN body, as the largest donor, is already causing stresses within the organisation, forcing it to focus – in the midst of a pandemic that has claimed over 620,000 lives globally – on how it will operate within renewed budget constraints.

Also at risk is the future of the US scientists seconded to the WHO and collaborative work with US public health bodies like the CDC (Centers for Disease Control and Prevention), the NIH (National Institutes of Health) and others that have been asked to look at what programmes should continue.

Perhaps most serious of all is the continued and misguided assault on any notion of multilateral institutions and the rejection that there is any reciprocal benefit to wealthy nations from organisations whose substantial function is helping the world’s poorest.

But above all this is what American diplomacy looks like in the Trump era.

It is ugly, dishonest, bullying and cruel, a pathetic trade in self-serving tittle-tattle that damages not only public health around the world, but undermines America’s claim to global leadership.