NEW YORK — A white supremacist pleaded guilty Wednesday to killing a black man with a sword as part of an attack that authorities said was intended to incite a race war in the United States. James Jackson admitted to fatally stabbing 66-year-old Timothy Caughman in March 2017 after stalking a number of black men in New York City. Jackson, who is white, told police he traveled from Baltimore to carry out the attack because New York is the media capital of the world.