‘I will tell you that attack on children yesterday had a big impact on me – big impact.” Those were the words of Donald Trump following the use of chemical weapons in Idlib province, Syria. With them, he sent the diplomatic world into a spin: had the president changed his mind on one of the most urgent foreign policy issues of our times?

As far as it’s ever possible to discern method in his madness, Trump’s attitude towards the war in Syria has been relatively straightforward. Destroying Isis is the priority, he has stated time and again, and if that means bolstering Assad as a side-effect, so be it. This has been the logic of his benign attitude towards Russia, too: Vladimir Putin is a Christian leader willing to use hard power against jihadist Islam, so he’s one of the good guys. Also, Iraq was a mess, and no one wants to start a third world war. Or, as he memorably put it back in November, “I had to listen to [Republican Senator] Lindsey Graham talk about, you know, attacking Syria and attacking, you know, and it’s like you’re now attacking Russia, you’re attacking Iran, you’re attacking.”

But as images of the dead and dying of Khan Sheikhun were beamed out across the internet and on TV, as Trump appointee Nikki Haley held up photos of them in the UN security council chamber in New York, the president seemed to be mulling a different approach. “My attitude toward Syria and Assad has changed very much … You’re now talking about a whole different level.”

This despite the fact that the Syrian civil war has been going on for six years, during which time, according to a 2016 report, there have been 161 chemical attacks. Despite the UN-documented use of sarin, mustard gas, VX and chlorine. Despite the fact that Samantha Power, Obama’s ambassador to the UN, delivered a speech notable for its similarity to Nikki Haley’s in December last year.

It remains to be seen what Trump’s response to this appalling episode will be, but there are ominous rumblings. Haley said: “There are times in the life of states that we are compelled to take our own action.” For defence secretary James Mattis, “It was a heinous act and will be treated as such.” Vice-president Mike Pence is now insisting that “all options are on the table”.

All this may just be routine strategic ambiguity. But, as ever with the Trump administration, we are in uncharted territory. No one quite knows whether Haley et al are speaking from a Trump-approved hymn-sheet, or concerned with protecting their own reputations in an administration not exactly known for its message discipline. No one quite knows whether Haley’s statement, only last week, that “Our priority is no longer to sit there and focus on getting Assad out,” will stand or be overturned. Since the latter would represent a 180-degree turn, however, it’s worth considering in more detail.

Those celebrating the possibility of a shift should ask how it may have come about. If there’s one thing we do know, it’s that Trump wants us to see that he cares. This is a president who is obsessed with how he is perceived, griping about unflattering photos and the size of the crowd at his inauguration.

It’s not even clear that he has any ideological aims, other than to win, and to be liked. He has, after all, donated to both Republicans and Democrats. He supported the Iraq war, then didn’t, then claimed that he never had. When Americans become conscious of an atrocity – despite the fact that it might be the latest in a long line of atrocities, many of which didn’t make the morning news – he can’t help but respond.

One theory about the demotion of Steve Bannon from the National Security Council on Wednesday is that the president disliked the amount of attention his adviser was getting. The Washington Post’s columnist Paul Waldman dubbed him “the most powerful person in the Trump White House”. Time magazine put him on the cover with the headline “the Great Manipulator”. The problem is, his boss doesn’t like to be outshone.

Perhaps the instant praise won by his UN ambassador prodded him into action. Regardless, the conclusion must be that any Syria “pivot” has its roots in Trump’s approval-seeking personality, his proneness to being thrown off course by media coverage, his shallowness of purpose.

This is why, rather than being reassuring, his sudden discovery of his conscience on Syria is profoundly disturbing. Major strategic decisions should not be made like this. Of course, Trump may simply sabre-rattle for a bit, then quieten down. But he might instead want a show of force. That could involve cratering a few runways, or something far more muscular. But these are decisions with consequences that would last far longer than the president’s attention span.

Whatever you think of the merits of western intervention in Syria, the idea of Trump directing it is, frankly, terrifying. And even though you may despise the current murky detente, so is the idea of this chaotic, underqualified White House being at loggerheads with Russia. The international order may be vulnerable, and dictators emboldened. But so long as this man is in charge, we must pray that the promise of an isolationist America is fulfilled.