The Trump Administration’s response to all this hasn’t exactly been a model of moral or strategic clarity. Mr. Trump has rambled from promising “severe” consequences to extolling U.S. arms sales to threatening sanctions to a seeming apologia for MBS as an “incredible ally.” On Saturday he finally got closer to the truth when he told the Washington Post that he doubted the Saudi explanation. “Obviously there’s been deception, and there’s been lies,” Mr. Trump said... Sanctions of individual Saudis under the Magnitsky Act are inevitable and warranted. Sanctioning MBS would depend on whether evidence implicates him in the killing. A moratorium on arms sales is probably counterproductive since MBS could turn to Russia and China. But the U.S. could work with the Saudis to reduce their bombing in Yemen, which is killing civilians, in return for U.S. interdiction of Iranian arms deliveries to Saudi enemies in Yemen.