On a scale of 1-10, how irritated is former Treasury Secretary Larry Summers by the Trump administration's escalating trade war? He's at an 11. On a special edition of GZERO World with Ian Bremmer, Summers says he is highly concerned with the White House's ad hoc and escalating imposition of tariffs, which he describes as the "worst, most consequential, self-inflicted wound in US economic policy since the Second World War." He believes that even if the tariffs are reversed, the US has already lost significant credibility globally, which will have long-term consequences for the country's ability to sell debt, form security alliances, and conduct economic and foreign policy.