The US military has taken several steps to protect its assets and equipment in the Middle East as the conflict between Israel and Iran continues, including evacuating all non-sheltered planes from its sprawling base in Qatar and moving US Navy ships stationed in Bahrain, two defence officials told CNN.

US Central Command has also pre-positioned additional supplies of blood in the region, the officials and a source familiar said, which is standard operating procedure any time there is a possibility of an attack on US forces.

One of the officials described the changes as prudent, precautionary planning amid threats by Iran that it will attack US troops and bases in the Middle East if the US decides to join Israel in striking Iranian nuclear facilities.