BRUSSELS - Nato foreign ministers are due to discuss ways to help Ukraine and reassure allies in Eastern Europe, at a meeting in Brussels.
It is the first time ministers from the 28 member states of the alliance have convened since Russia's takeover of Crimea caused a diplomatic crisis.
Nato has also bolstered air drills to be held over the Baltic states.
On Monday, Russia ordered a partial withdrawal of its troops near the eastern border of Ukraine.
Moscow is believed to have massed tens of thousands of soldiers there in recent days, causing alarm in Kiev and the West.
Russian President Vladimir Putin told German Chancellor Angela Merkel he had ordered the pullback, according to the German government.
Meanwhile, Russian energy firm Gazprom is increasing the price it charges Ukraine for gas from Tuesday.
Gazprom's chief executive Alexei Miller said the price of Russian gas for Ukraine had gone up to $385.5 (£231) per 1,000 cubic metres in the second quarter of 2014 from the previous rate of $268.5.
Mr Miller added that Ukraine's unpaid gas bills to Russia stood at $1.7bn.