Global leaders scrambled on Friday to convince the Ukrainian government and pro-Russian insurgents to halt nearly three months of fighting whose resumption has further upset East-West ties.
Clashes in the economically-vital industrial border regions of Lugansk and Donetsk picked up with renewed vigour when Ukrainian President Petro Poroshenko tore up a 10-day truce because of continuing rebel attacks.
Poroshenko's decision Monday was immediately followed by the launch of a "massive" offensive by Kiev that drew warnings from Russian President Vladimir Putin about his right to protect compatriots in Ukraine.
Donetsk authorities said the eastern city of nearly one million people was shaken overnight by the echoes of blasts from battles raging on its outskirts.
The local council in the separatist stronghold of Lugansk said one civilian was killed and at least eight injured by shelling.
Ukraine's military reported it lost one man in rebel raids that included brief assaults on airfields near Lugansk and the flashpoint city of Kramatorsk.
A spokesman for Kiev's forces claimed 150 pro-Kremlin gunmen had been "eliminated". Similar unverified claims, which the rebels deny, have been made throughout the conflict.
The uprising in eastern Ukraine was sparked by the ousting in February of a pro-Kremlin administration in Kiev, and was encouraged by Russia's subsequent seizure of Crimea.
So far it has claimed more than 460 lives and left parts of the industrial rustbelt in ruins.
The low-scale warfare on the European Union's eastern frontier has also unified the West in its biggest pushback to date against Putin's seeming attempt to reassert command over former Soviet lands.
Russia now faces the threat of devastating economic sanctions should Putin fail to explicitly order the militias to lay down their arms.
France and Germany -- still hoping to avoid new punitive steps that would damage their own economies -- are now spearheading efforts to set up new Contact Group discussions that until now have failed to yield results.
US President Barack Obama and British Foreign Secretary William Hague both called on Putin on Thursday to make sure the separatists attend the talks.
The Russian and Ukrainian foreign ministers agreed in Berlin on Wednesday to meet for talks involving separatist leaders and mediated by a European envoy by Saturday.
Unnamed sources told Russian media that the talks had been tentatively scheduled for Friday evening somewhere in Ukraine.
But Kiev refuses to convene the meeting again in rebel-held Donetsk -- a location backed strongly by Moscow.
- Russia as 'junior partner' -
The United States has preferred not to play a direct role in the negotiations after enraging the Kremlin by sending senior diplomats to Kiev in support of protests against the old pro-Russian regime.
Obama has had regular phone calls with European heads of state and Putin himself that underscored his concern about Russia's expansionist threat.
But Washington's long-distance approach has done little to appease Moscow.
"The United States believes that it won the Cold War and that Russia -- a successor to the Soviet Union -- lost," Deputy Foreign Minister Sergey Ryabkov told Moscow's Kommersant daily.
"And from this it concludes that Moscow must obey and conduct itself in international affairs, and in its relations with the United States, as a junior partner."
Poroshenko's security worries have been compounded by headaches over an imploding economy and Russia's decision in June to cut off its neighbour's gas supplies over disputed debts.
Ukraine is hoping to wean itself off its historic reliance on fuel from Russia. The finance ministry on Thursday published an eight-point blueprint on switching homes and heavy industry away from natural gas.
The long-term plan includes a greater reliance on coal -- a pollutant whose use has damaged the quality of life in countries such as China -- and construction of new plants for converting cheaper liquified natural gas imports from the United States and the Gulf.