Fragile peace talks aimed at ending the separatist war between Ukraine and pro-Russian rebels are due to resume Wednesday, a day after Kiev angered Moscow by taking a historic step towards NATO.
The talks in the Belarussian capital Minsk are expected to bring together envoys from Ukraine, Russia, pro-Moscow separatists and the Organization for Security and Co-operation in Europe (OSCE).
Progress in the peace efforts had been in doubt for more than two weeks and Tuesday's vote by the Ukrainian parliament to drop the country's non-aligned status put further pressure on the delicate process.
Russian Foreign Minister Sergei Lavrov reacted to the vote by demanding that the ex-Soviet state "put an end to confrontation" and stop adopting "absolutely counterproductive" measures.
And Prime Minister Dmitry Medvedev said even more bluntly that "in essence, an application for NATO membership will turn Ukraine into a potential military opponent for Russia".
President Petro Poroshenko had vowed to put Ukraine under Western military protection after winning an election following the ouster of Ukraine's then Moscow-backed president in February.
"European and Euro-Atlantic integrations -- that is Ukraine's single course," Poroshenko tweeted moments after the 303-8 vote in the government-controlled chamber.
Ukraine assumed de facto neutrality under strong Russian pressure in 2010. It had sought NATO membership in the early post-Soviet era but was never viewed as a serious candidate.
The revolution in Kiev upset Russian President Vladimir Putin's plans to enlist Ukraine in a new bloc he was forging in order to counterbalance NATO and the European Union.
And Moscow had set Kiev's exclusion from all military unions as a condition for any deal on ending the pro-Russian uprising that has killed 4,700 in the eastern Ukrainian rustbelt in the past eight months.
Putin's view of NATO as modern Russia's biggest threat has only been reinforced by this year's dramatic spike in East-West tensions over Ukraine.
Medvedev warned that Ukraine's rejection of neutrality and a new Russian sanctions law that US President Barack Obama signed on Friday "will both have very negative consequences".
"And our country will have to respond to them," he wrote in a Facebook post.
Perhaps the most immediate threat was to Wednesday's delicate talks, agreed by Poroshenko and Putin on Monday.
- Rebels head to Minsk -
The last two rounds of Minsk consultations in September produced a truce and the outlines of a broader peace agreement that gave the two separatist regions partial self-rule for three years within a united Ukraine.
But the deals were followed by more fighting that killed at least 1,300 people. The insurgents' decision to stage their own leadership polls in violation of the Minsk rules effectively ended political talks between the two sides.
A new meeting in Belarus had been hampered by Kiev's refusal to discuss lifting last month's suspension of social security and other benefit payments to the rebel-run districts.
Ukraine's leaders suspect the money is being stolen by militias in the Russian-speaking Lugansk and Donetsk regions and used to finance their war.
A Kiev-based representative for the Organization for Security and Co-operation in Europe (OSCE) who will attend Wednesday's meeting said the sides would discuss humanitarian aid deliveries but steer clear of the payments debate.
The OSCE's Heidi Tagliavini added that the other big points on the agenda included the details of a mutual troop withdrawal and a prisoner exchange.
But Donetsk rebel representative Andrei Purgin said his side would insist on raising the funding issue -- should the Minsk talks go ahead as planned.
Donetsk separatist envoy "Denis Pushilin is on his way to Minsk. But we still do not know if there will be negotiations tomorrow," Purgin told AFP by telephone on Tuesday.
Lugansk separatists said their envoy had also departed for Belarus for what they described as preparatory talks.
Self-declared Lugansk leader Igor Plotnitsky said he would personally attend a second meeting in Belarus on Friday should the sides agree the terms of a deal that met the rebels' main demands.