Rachel Maddow questions the Trump administration's use of National Guard and Marine troops in Los Angeles after National Guard troops marched through MacArthur Park on Monday in a show of force with no clear reason. According to reports, the park was largely empty with summer camp children playing outside when the federal troops arrived on horseback, in armored vehicles, dressed in military fatigues. For more context and news coverage of the most important stories of our day click here: https://