As Obama's adviser on Russian affairs, Michael McFaul helped craft the United States' policy known as "reset" that fostered new and unprecedented collaboration between the two countries. Then, as U.S. ambassador to Russia from 2012-2014, he had a front-row seat when this fleeting moment crumbled with Vladimir Putin's return to the presidency. "It's tragic," he says. "How is it that we have come back to something close to the Cold War?"