The Ukrainian president, Petro Poroshenko, has called for United Nations peacekeepers to be deployed to his country's eastern war zone and for Russia to end its support for separatist militia amid another deadly surge in violence.
During two hours of four-way telephone talks with the leaders of Russia, Germany and France, Mr Poroshenko said recent days were among "the bloodiest of 2017 and urged Russia to immediately cease aggressive actions and supply of weapons to the occupied territories".
Mr Poroshenko’s office said he also “emphasised the importance of deployment of a UN peacekeeping mission” in the Donbas region, where fighting since 2014 has killed more than 10,000 people and forced more than 1.5 million from their homes.
In the past week at least 15 Ukrainian soldiers have been killed and more than 20 injured in Donbas, and Kiev has claimed that Russian military strike forces have been observed moving towards the Ukrainian border.
"The Russian Federation is at liberty to change the configuration of its armed forces on its territory however much it considers appropriate," a Kremlin spokesman, Dmitry Peskov, said in response on Monday.
The Kremlin did not reveal what President Vladimir Putin said during the talks other than that he "expressed in detail the Russian positions on all key provisions" of the so-called Minsk agreements, which aim to end the conflict in Ukraine.
Merkel and Macron
The offices of the German chancellor, Angela Merkel, and the French president, Emmanuel Macron, did not immediately comment on the talks, but Mr Poroshenko's administration said they rejected "any statements that undermine Ukraine's territorial integrity, particularly as regards the establishment of the so-called Malorossiya".
Militia leaders announced last week that they want to transform Ukraine into a state called Malorossiya – a name used in tsarist times for a swathe of the Russian empire that is now Ukrainian territory.
Monday's attempt to reinvigorate the four-nation "Normandy" format of talks on implementation of the Minsk deal came as the United States seeks a bigger role in trying to resolve a conflict that has severely damaged East-West relations.
Kurt Volker, the newly appointed US special envoy to Ukraine, visited the government-controlled Donbas town of Avdiivka on Sunday, and spoke of the "terrible human cost" of the war on both sides of the front line.
“This is not a frozen conflict; this is a hot war. It’s an immediate crisis that we have to address as quickly as possible,” he said.
Asked if Washington believed Russia was to blame for the conflict, Mr Volker replied: “Yes, we do. We see what has happened, we understand the way this conflict has begun, we understand the way it is managed today, and that’s why it’s important for the United States to become more engaged, and that we try to find a way to change the strategic perspective here so that different decisions are made.”
Despite President Donald Trump’s calls for a rapprochement with Moscow, the United States Congress is expected to extend and tighten sanctions on Russia on Tuesday. The European Union fears the measures could harm energy projects between European and Russian firms.