Turkish tanks launch an attack on north-eastern Syria (Picture: PA).
Written by Hamish de Bretton-Gordon, former British Army officer and Syrian conflict expert
The US is clear, or least President Donald Trump is, that he will no longer guarantee the security of allies - especially if it does not have a direct threat to the US mainland.
North-eastern Syria is more than 5,000 miles from Washington DC and Mr Trump believes he is safe there - at least from the so-called Islamic State group (IS).
But this is not the same for the UK and Europe.
Syria is an eastern Mediterranean country and has direct access to mainland Europe.
There are four main challenges facing the UK and other European nations.
Firstly, the IS fighters currently in detention must be secured.
Mr Trump says they are Turkey's problem - Turkey says they are a European problem. Whatever, a solution is needed.
Even having these people behind bars in the European Union (EU) will be safer than having them roaming Europe, trying to cause, terror, death and destruction.
Secondly, the chance of escalation by accidental engagement with coalition forces must be avoided at all costs.
It is most likely the Peshmerga, the Iraqi-Kurd military who hold the border between Iraq and Turkey, could be engaged - mistaken for the Kurdish-led Syrian Democratic Forces (SDF).
Between 2015-2017, I was Peshmerga's chemical weapons advisor during their battles with IS.
Alongside the SDF, the Peshmerga are most responsible for the defeat of Islamic State's self-proclaimed caliphate - we owe both our help.
The Iraqi-Kurds are the UK's closest allies in the region - we owe them a huge debt of gratitude and we at least must stand with them now.
There are up to two million civilians in north-eastern Syria and there are already civilian casualties.
The potential for a massive humanitarian disaster is high and it is a possibility that these people may once again come under IS control with nowhere else to go.
Turkish President Recep Tayyip Erdoğan is also saying he will move the two million Syrian refugees in Turkey back into north-eastern Syria.
I was with these people in southern Turkey recently - most will not want to go.
They have built new lives - the prospect of going back to a war zone, which they already escaped at great peril, is not appealing.
Most would likely try and flee to Europe which would be equally terrible for them, as well as the EU.
Finally, while the world's attention is focused on the Syria-Turkey border, Syrian leader Bashar al-Assad and Russian President Vladimir Putin will up the genocide in the country's north-west, Idlib.
The Syrian government and Russian forces will retake the province where three million civilians live, causing thousands of deaths and potentially more refugees for Europe.
I was in Idlib a few weeks ago - the people there felt abandoned and now the people in the north-east feel the same.
So what? If we do nothing, the Syrian-Kurds may turn to the regime, Russia and Iran which is likely to broaden the conflict as I cannot see the Israelis taking this lying down.
This could easily produce an east-west conflict, with a NATO member fighting forces supported by Putin.
In the past, we could have expected the United Nations to get involved but it has become a 'paper tiger'.
The UN is now a place of words, not actions - Russia, Iran and the Syrian regime have all blocked and ignored their calls.
Against a useless UN and a disengaged US, unless we want to hand control of the Middle East and the Eastern Mediterranean to Russia and IS, then the UK and EU must engage and, if necessary, militarily.
We could provide a peacekeeping force and a no-fly zone between the Turkish buffer zone and the SDF.
Sir John Major did this after the first Gulf War in 1990 - it saved the Iraqi-Kurds from Saddam Hussein.
We must up our humanitarian efforts to support potentially five million civilian refugees and prevent a catastrophe of biblical proportions.