US Defense Secretary Mark Esper arrives in Saudi Arabia for an unannounced visit. -More to Follow Copy Related Stories Pentagon chief says keeping some troops in northeastern Syria under discussion US troops leaving Syria to go to western Iraq: defense chief Esper Pompeo: Aramco attack was Iranian, carried out with cruise missiles Trump to send more US troops in Middle East Ex-Pentagon chief Mattis warns US cannot survive without allies US asks S Korea to send troops to Strait of Hormuz