DONALD TRUMP’S inability to hold an idea in his head for longer than the average goldfish has left Theresa May doing her own fishy mouth-popping impressions, incapable of making a decision about Syria.

The “strong and stable” Prime Minister body-swerved our elected Parliament to push through a Cabinet decision to back military action after Trump’s infantile warning to Moscow to get ready for US missiles.

May, like every British prime minister since Winston Churchill, is so obsessed by the myth of a “special relationship” with Washington that she wanted to be sworn in as first deputy in the US sheriff’s posse.

Unfortunately for her — but possibly fortunately for the people of Syria and the wider Middle East — Trump has listened to sober voices in his own administration, especially Defence Secretary James Mattis.

Caution and moderation do not come naturally to General Mattis. His acknowledged nicknames “Warrior Monk,” “Chaos” and “Mad Dog” attest to that.

But, unlike Trump and George W Bush who are gung-ho for all US overseas wars but contrive to save their own hides by staying out of them by virtue of family contacts and sick notes, Mattis has combat experience in Iraq and Afghanistan.

He is aware of how errors can cause bloodshed and complicate a situation, not least when he gave the order to bomb a house on the Iraq-Syria border in 2004, causing what became known as the Mukaradeeb wedding party massacre in which 42 civilians died.

Gen Mattis understands that modern warfare is not simply a computer game where the death count piles up before everyone calls it a day and goes home for tea.

His insistence that the US, whatever its suspicions may be, doesn’t have evidence to pin the blame for a possible chlorine or sarin attack in Douma on Russia and his warning of the consequences of matters escalating out of control contrasts sharply with the ramblings of deceitful blow-hard Foreign Secretary Boris Johnson.

He, like May, is anxious to hitch a ride on the Trump battle wagon, confident that Britain’s role will be bombing targets in Syria with no consequence for people in this country or in the government.

For all their protestations of concern for the Syrian people, this approach is racist, disregarding harm to Arab civilians as long as Britain’s martial reputation is reaffirmed.

French President Emmanuel Macron, whose sycophants cast him as a latter-day Tony Blair, may not realise the disservice they do him, but, in truth, his dedication to pursuing war on a dodgy pretext does indeed define him as a Blairite.

He insists that he has “proof” of “at least chlorine” being used in Douma by President Bashar al-Assad’s forces, even though the allegations have only ever been based on a video put together by the Jaish al-Islam jihadist group and its collaborators.

If Paris has real proof, rather than this questionable video, it should share it with other governments and, especially the Organisation for the Prohibition of Chemical Weapons (OPCW) whose investigators should arrive in Damascus today.

Russian military police, who will provide security to the OPCW team, say their chemical and radiological security services have detected no traces of chemical agents in Douma and this will be confirmed, or not, by the global body.

It makes no sense for Nato air forces to complicate OPCW efforts by bombing military sites or, as Diane Abbott says, recalling what happened in Libya, “serving as the air arm of the jihadi extremist rebels.”