The US-Japan alliance is complex. But among other priorities, to rein in China, both countries need each other.

If you know anything about Rahm Emanuel, it's that speaking diplomatically may not be his forte. And yet, his current post demands it. The former White House chief of staff (called, in his day, a "pitbull") and the polarizing mayor of Chicago now serves as the US ambassador to Japan, one of the US' closest allies. Ian Bremmer was in Tokyo for an exclusive interview with Emanuel. And though the ambassador did his best to remain "diplomatic," there were flashes of the "pitbull" as well.