The European Union called Russia's aerial bombing campaign in Syria "dangerous" on 12 October. Speaking after a meeting of EU foreign ministers in Luxembourg, EU foreign policy chief Federica Mogherini warned air strikes designed to support Assad could also deepen the four-and-a-half- year civil war that has killed 250,000 people.

"Obviously there is a worry on the fact that military activities might be either not targeted against Daesh [Islamic State] or other UN-recognised terrorist organisations, and on the other side might not be coordinated with other actors that are playing a military role in this area, which is something dangerous in itself," Mogherini said.

She also called on Russia to be involved in talks on a political transition in the war-torn country. "But, on the other side, I have to underline because I've seen that especially this morning very few of you [journalists] if any at all have noticed that reference that the role that Russia can play in let's say exercising a sort of pressure or involvement of the regime in the political process itself. That is going to be a very significant and important role that Russia can play," Mogherini said.

While failing to agree on whether President Bashar al-Assad should have any role in ending the crisis, ministers sought to further pressure him by agreeing to broaden the EU's economic sanctions criteria to people benefiting from his government, a move essentially aimed at freezing the assets of the spouses of unnamed senior figures.

The EU's own position on Assad remained unclear, with no agreement on whether he could play a role in agreeing a ceasefire and paving the way for elections, or whether the president should go into exile or immediately to prison. Mogherini suggested contact with Assad should be made through the United Nations.

"The situation is still that of having Assad sitting in Damascus and terrorist organisations and in particular Daesh gaining ground in Syria but also in Iraq. So, the reality check means that it's not more of the same that is going to lead to the political process to start and to end with a transition but to have a different kind of approach, which means involving also representatives of the regime at the negotiating table led by the UN," Mogherini said.

After years of inaction in Syria, the EU is now desperate to stem the flow of migrants into Europe. Its stark criticism of Moscow underscores just how far diplomatic efforts have faltered since a UN meeting in New York in late September, when Europe and the United States looked to Russia for help.