Slavyansk:
Ukraine's new Western-backed leaders vowed on Wednesday to stick by their unilateral ceasefire and pursue peace talks despite the downing by pro-Russian militia of an army helicopter in the strife-torn separatist east.
The death of nine servicemen outside the rebel bastion of Slavyansk and loss of two troops in sporadic attacks prompted Ukrainian President Petro Poroshenko to threaten to unleash a powerful new military campaign in the Russified rustbelt.
An AFP team in Slavyansk heard a wave of shelling being launched by Ukrainian forces who have effectively surrounded the devastated city of nearly 120,000 on Wednesday morning.
Their assault was met with extended rounds of anti-aircraft and heavy machinegun fire that echoed through deserted city streets.
"This is the calm before the storm that begins once the ceasefire ends," said a 42-year-old rebel who is simply known to his unit as "Oleksandr the Soldier".
Poroshenko's ominous warning dented hopes of the sides mediating an end to 11 weeks of guerrilla warfare that has killed more than 435 people and brought the ex-Soviet nation to the brink of collapse.
Kiev's temporary ceasefire was picked up by rebel commanders on Monday but was due to expire on Friday morning after just two rounds of inconclusive talks.
Ukraine's Foreign Minister Pavlo Klimkin said he told his counterparts in Brussels on Wednesday that Kiev had thus far kept to its pledge to hold fire despite dozens of rebel raids.
"We are committed to do our utmost to achieve the de-escalation of the situation," Klimkin said during a meeting of top diplomats from the 28 NATO member states.
But a separatist leader in the self-proclaimed Donetsk People's Republic said after a second round of peace talks with Kiev that the truce was holding in name only.
"There is no ceasefire," Oleksandr Borodai said after a second round-table meeting with Kiev representatives in the regional hub of Donetsk since Monday.
"We are seeking peace. But for now, all the consultations have been useless," Borodai told reporters.
Poroshenko seeks Putin talksPutin has urged both sides to extend the truce and pushed senators to revoke his March 1 authorisation to invade his western neighbour in a bid to "protect" ethnic Russians from the nationalists now in power in Kiev.
Russia's rubber-stamp upper chamber approved Putin's request on Wednesday in a 153-1 vote.
But Kiev and Washington still accuse Putin of covertly arming the rebels in retaliation for the February ouster of a pro-Russian administration that abruptly ditched an historic EU agreement and preferred closer ties with Moscow instead.
US Secretary of State John Kerry said in Brussels that Russia must still take "many concrete" steps to end the crisis.
Poroshenko will sign the final chapters of that pact in Brussels on Friday despite the strong likelihood that Russia will follow up a cut in gas deliveries it imposed on June 16 with punishing new trade barriers.
"The near-term economic impact of this agreement will depend very much on how Russia responds," economists at London's Capital Economic consultancy said in a research note.
"However, the agreement, coupled with Ukraine's ($17.0-billion, 12.5-billion-euro) IMF deal, should act as an anchor for much-needed economic and political reforms which would boost growth over a medium-term horizon," it added in a report.
Poroshenko will also introduce to parliament on Thursday a draft of a new constitution that expands some regional powers but stops well short of creating a federation that Putin had hoped would give the east a chance to build much closer ties with Moscow.
The Ukrainian leader had German Chancellor Angela Merkel and French President Francois Hollande join him for a conference call with Putin that Paris said lasted more than an hour but whose details were not immediately released.
The French presidency said Hollande and Merkel "encouraged" Putin and Poroshenko to "work together, especially in order to put in place a mechanism to oversee the truce".
NATO warns RussiaNATO foreign ministers huddled in Brussels amid pleas from ex-Soviet satellite nations for the Alliance to beef up its military presence along Russia's western frontier.
NATO chief Anders Fogh Rasmussen noted entering the meeting that the Alliance intended to "review our relations with Russia and decide what to do next".
"I regret to say that we see no signs that Russia is respecting its international commitments," NATO's top civilian official said.