American Defense Secretary James Mattis said Tuesday that the US is not coordinating its military operations in Syria with Russia although it continues "to deconflict with the Russians for safety of flight, to avoid any kind of misunderstanding, or any kind of inadvertent running into each other". As for the war in Yemen, he denounced the firing of Iranian-supplied missiles into Saudi Arabia by the Houthi rebels, saying "this is something, with the number of innocent people dying inside Yemen, that has simply got to be brought to an end." He made the comments while en route to Riyadh, the first stop of his trip to the Middle East and the Horn of Africa. Mattis arrived in Cairo on Wednesday.