KYIV, Jan 13 – Russian President Vladimir Putin will probably not launch a major invasion of Ukraine, because he understands that this threatens with serious Western sanctions against the Russian Federation and the strengthening of Ukraine's weapons, Senior Director of the Atlantic Council's Eurasia Center, U.S. ambassador to Ukraine in 2003-2006 John Herbst said.

"I am at least a little bit optimistic that we're not going to see Putin launch a major invasion of Ukraine with his 100,000 troops. There may be a limited military action, not insignificant. I think he understands that there's going be some very serious sanctions and there'll be more arms for Ukraine, and there'll be a strengthening of NATO's force posture in the East," Herbst said in during the discussion held by the Kyiv Security Forum on Wednesday.