By John Irish and Robin Emmott
PARIS/BRUSSELS (Reuters) - Turkey's offensive on Kurdish-led forces in Syria has left its European allies incensed and fearing new jihadist militancy, but they are scrambling to form a coherent response beyond refusing to pay for any new humanitarian crisis on their doorstep.
Turkish troops and their Syrian rebel allies pushed further into Syrian territory on Thursday, opening up a new front in the eight-year-old Syrian civil war, and exposing Europe's powerlessness and inability to influence the direction of the conflict.
The assault, which began after U.S. President Donald Trump pulled American troops out of the way, also raises fundamental questions over the fate of EU-Turkey ties and further strains transatlantic relations, including trust within the NATO military alliance, diplomats and officials said.
It complicates further any prospect of Ankara joining the European Union and threatens a migration deal between Brussels and Ankara that has slashed refugee numbers entering the bloc but which was under renewed pressure by new refugees trying to reach Europe.
"This is a recipe for disaster, be it for the Turks, the Kurds or us," said a senior European diplomat. "This Turkish intervention is a complete distraction that will open up a Pandora's box."
Ankara has said it intends to create a "safe zone" to return millions of refugees to Syrian soil, for which it wants Europe to pay, a plan European diplomats have said is unrealistic.
All 28 EU governments on Wednesday rejected those plans, saying it would not provide aid and warned that such an idea would not past muster with the United Nations.
European Commission President Jean-Claude Juncker was blunt, saying: "Don't expect the EU to pay for any of it."
PUT EUROPE'S HOUSE IN ORDER
But how much Europe can do to pressure Ankara is unclear. It relies on Turkey to curb the arrival of refugees into Europe following a 2016 agreement to seal off the Aegean route after more than 1 million people entered the bloc.
Those numbers have picked up and coincide with Turkey, which hosts 3.6 million Syrian refugees, threatening to "open the gates" to allow those already in the country to head for Europe unless it receives support for its plans.
"We have put ourselves in a position where the Turkish-EU relationship is one-dimensional, based on one topic that has created a balance of power that disfavors us," said a European diplomat of the 2016 migration deal.
"We need to put our house in order. There hasn't been a collective solution to the refugee problem so we find ourselves exposed to this blackmail."
At a closed-door meeting on Tuesday, NATO envoys expressed alarm at Turkey's plans and sought to pressure Erdogan not to go ahead with any operation, diplomats said.
However, there was also recognition in the alliance that there was nothing it could do to stop Turkey because NATO is not active in Syria and there was no demand for a NATO role.
ISLAMIC STATE RETURN
Even more pressing for Europe is the fate of its Kurdish ally and a potential resurgence of Islamic State militants, which the Europeans are especially sensitive to after several major deadly attacks in the bloc.
Both French and British special forces operate with the Kurds in the region and their militaries provide air support and training for Kurdish forces, who until the Turkish offensive continued operations hunting down existing Islamic State cells.
Trump's decision to pull back, while not unexpected, has left those two nations particularly exposed. French and British officials acknowledge that if the United States were to fully withdraw they would have no choice but to also draw back.
"Betraying the Kurds would be morally awful but let's not fool ourselves: with or without Allied forces in northern Syria, the U.S. and Europe don't have any identifiable and credible policy to ending the Syrian civil war," France's former envoy to Washington, Gerard Araud, said on Twitter.
Europe's immediate fears center on militants regrouping, but also the threat of thousands of foreign fighters held by the Kurds escaping prisons.
The reaction from Trump - who has previously pressed reluctant European nations to take back their nationals among the Islamic State fighters captured on the battlefield in Syria - has done nothing to placate his allies.
"They'll be escaping to Europe, that's where they want to go. They want to go back to their homes but Europe didn't want them," he told reporters.
Czech Foreign Minister Tomas Petricek summed up European frustration, saying "unfortunately, at this point we have no other possibility than diplomatic pressure in order to calm the situation".
(Writing by John Irish; Editing by Alex Richardson)