KIEV: Ukrainian troops backed by tanks and fighter-bombers pressed Wednesday with a renewed offensive against pro-Kremlin insurgents that has drawn Russian ire but also vital U.S. support.
The return of all-out fighting in Europe's worst security crisis in nearly two decades set off a new international scramble to dampen hostilities in the strategic ex-Soviet state.
A diplomatic source said that the Russian and Ukrainian foreign ministers would meet their counterparts from Germany and France in Berlin later Wednesday in a bid to find some common ground that could establish a long-term truce.
But Ukrainian leaders said that their military operation was progressing with a resolve to stand up to what they see as a last-ditch Russian effort to halt their new westward drive.
"The armed forces and the National Guard are continuing an aggressive offensive against terrorists and criminals," parliament speaker Oleksandr Turchynov told lawmakers.
"Our soldiers' actions are sufficiently effective and productive," he said in televised remarks.
The border guard service in Kiev said that militias killed one Ukrainian soldier and wounded four others in separate mortar fire attacks along the Russian border.
It was the first casualty reported by Kiev in the second stage of the low-scale war. Regional officials had also confirmed Tuesday the deaths of four civilians in a roadside attack on their bus.
Ukrainian President Petro Poroshenko Monday took the risky step of contradicting his European allies for the first time since his May 25 elections by ripping up a 10-day ceasefire.
The decision was followed with the military's announcement of a "massive" operation in the eastern rustbelt designed to pound the rebels into submission and end the country's worst crisis since independence through force.
Russian President Vladimir Putin said that Poroshenko now bore full responsibility for the deaths that would follow in an offensive that has already claimed more than 450 lives in 11 weeks.
The warning appeared designed to show that Putin had until now been willing to work with the new Ukrainian leader despite the February ouster of a pro-Kremlin administration in what Moscow branded a "coup."
Putin and Poroshenko had spoken by phone regularly before the ceasefire in a bid to draft a joint peace plan that could ultimately normalize the ex-Soviet neighbor's relations.
But tensions between Moscow and Kiev now appear ready to soar again - a worrying turn of events for European leaders who will face added pressure to unleash punishing sanctions against Russia that would likely hurt their own economies.
Poroshenko's order to relaunch the eastern campaign was met with a deafening silence in European capitals.
But Washington immediately rallied to the Kiev's defense with a vigor reflecting the Cold War-like chill that has recently enveloped its relations with the Kremlin.
"President Poroshenko put in place a seven-day ceasefire. He abided by it. He extended it for three days, but the fact remained that the separatists, many of them were not adhering to it, and he has a right to defend his country," said U.S. State Department spokeswoman Marie Harf.
"The Ukrainian forces have a responsibility to defend their territory and their people. And what they are seeing is aggression by Russian-backed separatists that they have an obligation to respond to."
An EU diplomat told AFP Tuesday that the European Union was preparing new punitive measures that for the moment stopped short of an all-out restriction of the 28-nation bloc's banks from working with their Russian counterparts.
But the source added that the EU was not yet ready to target entire sectors of Russia's economy - a step now being weighed in Washington - and only preparing to extend its punitive measures "quantitatively and qualitatively."
Putin had appeared in past weeks to soften his public approach to Ukraine in the face of the Western sanctions threat.
He had pressed for direct negotiations and a long-term truce. Western powers had also reported a significant withdrawal of Russian forces from the border with Ukraine.
But Putin has notably refused to meet the main Western demand of calling on the rebels to lay down their weapons and relinquish control of roadblocks and border crossings across Lugansk and Donetsk.