Wherever US policy on Syria settles in the coming weeks and months, damage has already been done. Two announcements within a few hours encapsulated both the style of Donald Trump’s presidency (personalised, ignorant and erratic) and its perils. The first, a White House statement, followed a phone call with the Turkish president, Recep Tayyip Erdoğan, and blindsided everyone, including parts of Mr Trump’s administration. It not only announced the abrupt decision to withdraw troops from the north-eastern area bordering Turkey, abandoning the Kurdish-led Syrian Democratic Forces with which the US has partnered, but gave the green light to a Turkish invasion. The second – a tweet, following a furious backlash even from his own party at the prospect of further chaos in a desperately unstable region – announced that should Ankara do anything that “I, in my great and unmatched wisdom, consider to be off limits, I will totally destroy and obliterate the Economy of Turkey”.

But Ankara sees the SDF as indistinguishable from Kurdish insurgents inside Turkey and has long sought to eradicate them. Now it is poised to launch an offensive – likely to boost Mr Erdoğan’s flagging domestic popularity. It then wants to move many of its 3.6 million Syrian refugees – a source of growing complaints at home – to the area, reengineering its demography. Turkey never forgave its ally for partnering with the SDF; but Mr Erdoğan may now find that thanks to Mr Trump he has taken on more than he can manage.

Despite their critical role in tackling Islamic State, the Kurds, with whom the US has a transactional relationship, cannot be surprised to be dropped yet again – especially by a man who sees his re-election prospects as resting in part on bringing US soldiers home. It is only 10 months since James Mattis resigned as defence secretary after the president said he was withdrawing US troops. In the event, the Pentagon halved troop numbers and did its best to keep the mission out of Mr Trump’s eyeline.

Officials have briefed only that 50-100 troops are being redeployed from the border area to elsewhere in Syria; around 1000 are stationed in the country. Even Mitch McConnell, the Republican senate majority leader, warned that withdrawal “would only benefit Russia, Iran, and the Assad regime” – with which the Kurds will now need to cut a deal. He also warned that it would increase the risk of Isis regrouping; there are already signs of a resurgence. If the SDF ability to hold 90,000 prisoners with links to Isis is fragile, the idea of handing them over to Turkish forces, as Mr Trump mooted, is far-fetched – unless the US is inviting Turkey not only into the safe zone on the border, but all Kurdish-controlled territory. The risk that they could simply go free is real.

If Mr Trump’s overall direction of travel was predictable, its abruptness and the lack of a roadmap are nonetheless shocking. It is possible that the worst-case scenario – a new humanitarian catastrophe and the revitalisation of Isis – may be averted, depending on where the US administration’s thinking lands, and how the other parties respond. But the risks posed by Mr Trump’s foreign dealings are only increasing as 2020 approaches and as the impeachment process gathers pace. One does not need to romanticise past US foreign policy to recognise the dangers when there is no strategy at all, but a series of inconsistent, unpredictable pronouncements and actions. The flip-flops may make it appear as if the damage wrought by Mr Trump is containable. But they are part of the problem. The issue is fundamental, and devastating.