SINCE THE BRUTAL murder of Saudi dissident and Washington Post contributor Jamal Khashoggi last October, Congress has increasingly pressured the Trump administration to stop backing the Saudi Arabia-led coalition fighting in Yemen and halt U.S. arms sales to Riyadh. In response, President Donald Trump has repeatedly said that if the U.S. does not sell weapons to the Saudis, they will turn to U.S. adversaries to supply their arsenals.