Ukraine crisis: 'No miracles' at Berlin talks
German Chancellor Angela Merkel has said talks with Russian, Ukrainian and French leaders about a stalled Ukraine peace deal "didn't achieve miracles".
All sides have agreed to draw up a roadmap by the end of November on how to implement the Minsk peace deal.
Mrs Merkel, Russian President Vladimir Putin and French President Francois Hollande also discussed Syria.
The German leader said she and Mr Hollande had a "difficult conversation" with Mr Putin.
Both condemned Syrian and Russian air strikes on Aleppo.
The Ukraine discussions took place against a backdrop of tensions elevated by Russia's military backing for the Syrian regime - and a bombing campaign in Aleppo which the European Union has warned could amount to war crimes.
A blizzard of telephone diplomacy over the past week - when Mr Putin postponed a visit to France over a row about Syria - is said to have resulted in Wednesday night's meeting, which attracted several protest groups outside.
The 2015 Minsk agreement eased fighting between Ukrainian forces and Russian-backed rebels in the east of the country, but violence frequently flares along a demarcation line.
Speaking after the Berlin talks, President Poroshenko said all sides had agreed that a road map would be drawn by the end of November on how to implement the 2015 agreement and also protocols reached in 2014.
He also said Russia had agreed with a proposal to allow the deployment of an armed police mission from the Organisation for Security and Co-operation in Europe.
President Putin has made no official comments on the issue.
Ukraine, Western leaders and Nato say there is clear evidence that Russia has supplied the rebels with heavy weapons and regular troops. Russia denies that, but it is hostile to the Kiev government and openly supports the rebel cause.
In 2014, Russia annexed Ukraine's southern Crimea peninsula - a move condemned by Kiev and the West.
The last four-way meeting in the so-called Normandy Format took place in Paris in October 2015.
Mrs Merkel's spokesman Steffen Seibert told reporters to limit their expectations to a "brutally honest assessment of the situation" in Ukraine, while Mr Putin's spokesman Dmitry Peskov agreed that "obstacles" to implementing the Minsk accord should be identified.
Meanwhile, President Petro Poroshenko said he was not optimistic about the negotiations over the conflict, which has claimed nearly 10,000 lives since it erupted in 2014.
He will leave the table when what Mr Seibert termed the "catastrophic situation" in Syria is raised.