Official Moscow has announced that countries deploying peacekeepers to Ukraine will engage in "direct armed conflict" with Moscow and will respond "with all available means."
Ukraine has asked its European allies to deploy military "contingents" on its territory after the end of the three-year conflict, in order to protect itself from future attacks by Russia.
France and the United Kingdom have suggested they could deploy peacekeepers, but Moscow has rejected the idea as part of a ceasefire or as a long-term security guarantee for Ukraine.
"It is absolutely unacceptable for us that military units of other countries are stationed in Ukraine under any flag," Foreign Ministry spokeswoman Maria Zakharova said at a briefing on March 13.
"Whether it's a foreign contingent or a military base, all of this would mean involving these countries in a direct armed conflict with our country," Zakharova added.
Her comments come after US negotiators traveled to Russia to present their plan for a 30-day ceasefire in Ukraine, after receiving support for the plan from Kiev earlier this week.
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