On this edition of Press Conference USA, host, Kim Lewis talks with William Perry, Former US Secretary of Defense and Tom Collina, Ploughshares Fund Policy Director about their co-authored book, "The Button. The Nuclear Arms Race and Presidential Power from Truman to Trump." As the world marks the 75th anniversaries of the bombings of Hiroshima and Nagasaki, the book explores issues of the uncertain control of nuclear weapons and why the US should revise its nuclear weapons policy. The authors reflect on the use of the most powerful weapons ever to be used against other humans.