The decision follows an attack on Saudi oil fields.
US President Donald Trump has authorised the deployment of troops to Saudi Arabia and the neighbouring United Arab Emirates, to protect US oil interests in the region.
The decision follows an attack by Yemeni Houthi rebels on Saudi oil fields last week, which knocked out half of the country's oil production. Trump has advanced the narrative that the drone attack on the oil fields was backed by Iran.
The size of the deployment has not yet been determined, but Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff, has said it will be in the hundreds, rather than the thousands. It has also been maintained that the role of the military will be purely defensive in nature.
The US has also announced its intention to "accelerate the delivery of military equipment" to both nations.
Military build-up in the region is a sign of the escalating nature of the conflict.
Last week, Iranian Foreign Minister Mohammad Javad Zarif tweeted: "US is in denial if it thinks that Yemeni victims of 4.5 yrs of the worst war crimes wouldn't do all to strike back."
At least 130 children are dying per day of the famine in Yemen, and 13 million people total face starvation.