Nordic and Baltic foreign ministers on Friday demanded Russia immediately free an Estonian policeman charged with espionage in a case that has heightened tensions between Estonia and its Soviet-era master. 

Russia on Friday slammed the European Union for adopting new sanctions against Moscow during a week-old ceasefire agreed for conflict-riven eastern Ukraine.

"We believe that adopting such decisions at the very moment when the peace process in Ukraine is gaining strength -- we are hoping -- ... this means choosing a path towards undermining the peace process," Russian Foreign Minister Sergei Lavrov said in televised remarks on the sidelines of a security summit in the Tajik capital Dushanbe.

A senior Ukrainian defense official said on Thursday there was no contradiction between President Petro Poroshenko's announcement of a major Russian troop withdrawal and NATO's assertion that 1,000 Kremlin troops remained in the eastern war zone.

The high-ranking official said Ukrainian military assessments had shown up to 5,000 Russian soldiers crossing the border to bolster the pro-Kremlin uprising that began in mid-April and escalated in recent months.

U.S. President Barack Obama said Thursday that the United States would intensify sanctions in the defense, finance and energy sectors to punish Russia over its "illegal actions" in Ukraine, as the European Union said it could lift a new set of sanctions if a Ukraine ceasefire holds.

Obama said in a statement the move would worsen the Kremlin's deepening political and economic isolation.

For the Ukrainians who have fled the war zones of the east, life has become a grim daily grind of battling red tape and trying to find food, jobs and shelter.

The European Union failed to reach agreement on when the latest economic sanctions against Russia should be implemented and will meet again Thursday for more talks, a diplomatic source said.

The 28 member state ambassadors to the EU will "continue today's discussion on the restrictive measures, allowing for further assessment of the situation on the ground and additional consultations," the source said.

Russian President Vladimir Putin on Wednesday emerged from a Moscow church and told journalists he had lit a candle in memory of those who died defending separatist eastern Ukraine.

"Who did I light a candle for? For those who were injured and those who gave their lives defending people in Novorossiya," Putin said, shown on Russian television.

House Speaker John Boehner announced Wednesday he will invite Ukraine's President Petro Poroshenko to address a rare joint meeting of the U.S. Congress on September 18.

"Having President Poroshenko address Congress is another signal of our steadfast commitment to the aspirations of his people," Boehner said in a statement.

At the last checkpoint before the airport in Ukraine's main insurgent bastion of Donetsk, separatist fighters manning the barricades are dismissive of suggestions that the ceasefire is holding.

"Here's your ceasefire," scoffed Dmitry, pointing to the fin from an exploded mortar round, lined up with another three against a wall at the Putilovskiy Bridge checkpoint to the north of the city.

Crimea's Kremlin-loyal leader on Wednesday said that if the world recognizes an independent Scotland, then it should also offer similar recognition to the Black Sea peninsula which has joined Russia.

Acting regional head Sergei Aksyonov said that the West would have "no other option" but to back Crimea's move to break away from Ukraine, if it also accepts a Scottish vote to split from the United Kingdom.