The Ukrainian parliament has set the country on a course to join Nato by voting to drop its non-aligned status.
Lawmakers in Kiev overwhelmingly voted by 303 to nine on 23 December to pass a motion to cancel a previous law barring Ukraine from entering any military bloc.
Supporters of the move claimed it was necessary in the wake of the ongoing Kremlin-backed insurgency in the East and Russia's annexation of the Crimean Peninsula in March.
Moscow, which has long opposed a possible Ukrainian bid to join Nato, condemned the vote.
"This is counterproductive, it only heats up the confrontation, creating the illusion that accepting such a law is the road to regulating the deep internal crisis in Ukraine," said Russian Foreign Minister Sergey Lavrov.
The vote does not immediately translate into Ukraine applying to join Nato but both Ukraine President Petro Poroshenko and Prime Minister Arseny Yatsenyuk have previously stated is the government's goal.
"In the conditions of the current aggression against Ukraine, this law opens for us new mechanisms," Ukrainian Foreign Minister Pavlo Klimkin added, addressing the parliament.
Ukraine first applied to join the US-led alliance in 2008, under the pro-Western presidency of Viktor Yushchenko, but the request was turn down under strong pressure from Russia.
As Viktor Yanukovych came to power in 2010, the parliament approved the legislation concerned by today's vote, stating that Ukraine held a neutral status, thus preventing it joining any military alliance, including Nato.
Yanukovych was ousted by a pro-European revolution earlier this year.