Second, President Obama should dispatch Secretary of State John Kerry and Defense Secretary Chuck Hagel to Kiev to show U.S. support for Ukraine’s transitional government, and urge our allies in the European Union and NATO to send representatives there as well. The United States should convene an emergency meeting of NATO to develop a strong united response from the trans-Atlantic alliance. And we should send high-level delegations to our allies in Central and Eastern Europe to reinforce the fact that we are standing by them. As part of this work with our allies, we should develop a series of economic and security assurance measures to help the transitional government in Kiev remain stable and carry out a democratic transition.

Third, the United States should rally our allies to boycott this June’s G-8 summit in Sochi, Russia. And if Russian troops do not leave Ukraine immediately, Russia should be expelled from this group altogether.

Fourth, any and all discussions and negotiations with Moscow on any issue unrelated to this crisis, including trade and other matters, should be immediately suspended.