President Vladimir Putin has said Russia poses "no threat to anyone" and does not intend "to get involved in any geopolitical games or intrigues."
Addressing a meeting with military chiefs in the Black Sea resort of Sochi on November 26, Putin said Russia would "securely safeguard" its sovereignty and integrity and that of its allies.
The Russian president also drew "special attention to the need for a comprehensive approach and the unification of efforts of all government bodies in tackling tasks in the sphere of defense."
Putin’s comments come as the conflict in Ukraine, where government forces have been battling pro-Russian separatists since April, has brought ties between Moscow and the West to post-Cold War lows.
Kyiv and the West accuse Russia of directly supporting the rebels, which Moscow denies.
Russian also annexed Ukraine’s Crimean Peninsula in March.
Earlier on November 26, the U.S. general who is NATO's senior commander in Europe said that there was a large number of Russians providing "backbone guidance and training" to separatist forces in eastern Ukraine.
Speaking during a visit to Kyiv, U.S. General Philip Breedlove also promised that the United States will support Ukraine in the face of an "immediate threat from Russia" to its sovereignty.
He said the United States would help Ukraine pursue a diplomatic solution to the conflict with pro-Russian separatists that would respect the country's sovereignty and territorial integrity.
Breedlove expressed deep concern over "the militarization of Crimea," saying, "We are concerned that the capabilities in Crimea that are being installed" would enable Russia to "exert military influence over the Black Sea," he told a news conference.
Russia's Defense Ministry said on November 26 that it had deployed a batch of 14 military jets to Crimea, as part of a squadron of 30 that will be stationed on the peninsula.
Breedlove also said that, in addition to a sizable Russian force with a "coercive capability" near the border, "we still see a large number" of Russians within Ukraine "who are involved primarily in training, advising, assisting, and helping the forces of the Russian-backed forces in the east."
But he said, "We don't see [Russian] combat formations" on Ukrainian territory.
Russia denies involvement in the conflict, despite what Kyiv and NATO say is clear evidence of direct military support for the separatists in the conflict, in which more than 4,300 people have been killed since April.
Breedlove, who was in Ukraine in his U.S. capacity, earlier met with President Petro Poroshenko and Prime Minister Arseniy Yatsenyuk.
In Berlin, German Chancellor Angela Merkel said Russia's actions in Ukraine are a violation of international law and a threat to peace in Europe.
Merkel, in an address to Germany's lower house of parliament, said, "Nothing excuses or justifies Russia's annexation of Crimea and nothing justifies the direct or indirect participation of Russia in the fighting in Donetsk and Luhansk."
She told the Bundestag that Russia's actions had "called the peaceful order in Europe into question and are a violation of international law."
But Merkel warned that the West will need "patience and staying power" to deal with the problems posed by Russia's seizure of Crimea in March and support for pro-Russian separatists in eastern Ukraine.
Merkel said Germany would use all opportunities it can for "achieving a diplomatic solution in a dialogue with Russia."
But with fighting continuing despite a September cease-fire, she said economic sanctions against Russia "remain unavoidable," while "economic and political support should be provided for Ukraine."
Russia and Germany have close business ties, but their relationship -- which Russian President Vladimir Putin has made clear he sees as a priority -- has been badly strained by the Ukraine crisis.
Merkel's remarks reflect growing German frustration over Moscow's refusal to heed Western calls to stop supporting the separatists, who have seized control of large parts of Donetsk and Luhansk.
A recent visit to Kyiv and Moscow by German Foreign Minister Frank-Walter Steinmeier, who met with Putin, failed to produce a breakthrough.
Merkel spoke a day after Ukraine leveled fresh charges that Russia is sending military support to the separatists.
Foreign Ministry spokesman Yevhen Perebyinis said on November 25 that five columns of heavy equipment were spotted crossing into Ukrainian territory on November 24.
Meanwhile, Lithuanian Foreign Minister Linas Linkevicius has said “the key to the solution” of the Ukrainian crisis is in Moscow.
Speaking on November 26 to RFE/RL's Ukrainian Service in Prague, Linkevicius said, "We are dealing with an external aggression because we know that there are troops, rocket launchers, and tanks flowing [into Ukraine] from outside and this amounts to a state level of support."
Meanwhile, Russia’s envoy to the United Nations has voiced skepticism about a request from pro-Russian separatists in Ukraine for a UN peacekeeping force.
Asked about the appeal, Vitaly Churkin said on November 26, "I think it's unlikely."
The AFP news agency quoted a senior European diplomat as saying there was no enthusiasm for mounting a peace operation in east Ukraine.
On November 25, leaders of the self-proclaimed Donetsk People's Republic called for the intervention of a UN peacekeeping force that included Russians.
The Ukrainian government suggested it was a pretext to invite Russian troops onto its territory.
With reporting by Reuters, Interfax, AP, and TASS