(Credit: AP/Evan Vucci) How do you keep an impulsive and ignorant president, a man who has been described by his own Secretary of State as a “f**king moron,” from launching a nuclear war? That terrifying question, often asked worriedly, privately or rhetorically over the last months, is echoing ever more loudly this week after President Trump insulted another inexperienced authoritarian nuclear commander, North Korea’s Kim Jong-un. Trump described Kim as “short and fat,” and the 33-year-old dictator responded by sentencing Trump to death. The nightmare of nuclear-armed boys in the playground of geopolitics has come to life. The U.S.