Ivan Krastev

The United States and Russia probably do not have common aims and dreams, but they have common worries: Both Washington and Moscow are concerned about the rise of China and are threatened by the rise of radical Islam.

America gave the world the notion of the melting pot - an alchemical cooking device wherein diverse ethnic and religious groups voluntarily mix together, producing a new, American identity. And while critics may argue that the melting pot is a national myth, it has tenaciously informed the America's collective imagination.

We need to have a national security that puts steel in front of our enemies. I would send weapons to Ukraine. I would work with NATO to put forces on the eastern border of Poland and the Baltic nations, and I would reinstate, put in place back in the missile defense system that we had in Poland and in the Czech Republic.