The likelihood that Russia will invade Ukraine seems to be growing by the day. If Russia indeed attacks Ukraine, how should the United States and Europe respond?    Joining me to take on that question and more are four excellent speakers: Andrew Weiss of the Carnegie Endowment for International Peace Nina Jankowicz the Woodrow Wilson Center Jim Goldgeier of Stanford's Center for International Security and Cooperation.   Melinda Haring of The Atlantic Council     Recorded live via Twitter Spaces. Follow me @MarkLGoldberg to be notified of the next live taping.