The US has approved plans for a series of strikes on Iranian targets in Syria and Iraq.
Officials say the strikes would take place over a number of days, and weather conditions will likely dictate when they are launched.
It comes after a drone attack killed three US soldiers in Jordan, near the Syrian border, on Sunday.
The US has blamed an Iranian-backed militia group for the attack.
The Islamic Resistance in Iraq – which is believed to contain multiple militias that have been armed, funded and trained by Iran’s Revolutionary Guards force – has said it was responsible for the strike.
Iran has denied any role in the attack which injured 41 other US troops at the military base.
While US officials have pledged to respond to the drone attack, President Joe Biden and other officials have said the country is not seeking a wider war with Iran.
Several Iran-backed groups have increased attacks on US and Israeli-linked entities since the beginning of the Israel-Hamas war on 7 October
