From CNN's Nic Robertson in Riyadh, Mohammed Tawfeeq in Baghdad and Barbara Starr in Washington

Iraqi Prime Minister Adil Abdul Mahdi said Iran sent Iraq an official verbal message that an attack “had begun or would begin shortly,” on unspecified US military locations -- but other informed sources are contradicting that timeline.

An Arab diplomatic source told CNN that Iraq gave advance warning to the United States on “which bases would be hit” after Iranian officials passed on the information.

A US defense official said Iraqis were told by Iran to stay away from certain bases.

CNN has reported that US intelligence had observed Iran moving military equipment including drones and ballistic missiles over the last several days.