President Donald Trump's staunchest allies voiced outrage Monday after he suddenly declared that U.S. troops would allow Turkey to attack Syrian Kurds who have fought as U.S. allies for years to tamp down the Islamic State. The president later threatened to destroy the economy of Turkey, a NATO member, if it goes too far against the Kurds. But that did little to mollify concerns overseas or in Congress after Trump announced that the U.S. would withdraw troops and get them out of the way of Turkish forces. Sen. Ted Cruz of Texas said it would be "disgraceful if we sat...