The Pentagon said on Friday that the US will deploy additional troops and military equipment to Saudi Arabia and the United Arab Emirates to beef up security, as President Donald Trump has at least for now decided against any immediate military attacks in response those on the Saudi oil industry.

Secretary of Defense Mark Esper said this is the first step, and he is not ruling out additional moves down the road. He said it is a response to requests from the Saudis and the United Arab Emirates (UAE) to help improve their air and missile defences.

Esper and General Joseph Dunford, chairman of the Joint Chiefs of Staff, said details of the deployments will be determined over the coming days.

Saudi and US officials have said that evidence shows Iranian involvement in last weekend's attacks - an allegation Tehran denies. 

Yemen's Houthi rebels, who have been locked in a war with a Saudi-UAE-led coalition since 2015, claimed responsibility for the attacks, warning Saudi Arabia that their targets "will keep expanding".

On Friday, an official with the Houthi rebel movement in Yemen said it will stop aiming missile and drone attacks at Saudi Arabia, warning that a continuation of the war could lead to "dangerous developments".

Moderate number of forces

The Pentagon said the US troop deployment would involve a moderate number of forces - not numbering thousands - and would be primarily defensive in nature. It also detailed plans to expedite delivery of military equipment to both Saudi Arabia and the UAE.

"We will also work to accelerate the delivery of military equipment to the Kingdom of Saudi Arabia and the UAE to enhance their ability to defend themselves," Esper said. 

Dunford said officials were still hammering out the best array of capabilities to defend Saudi Arabia, noting the difficulty combating a swarm of drones.

"No single system is going to be able to defend against a threat like that, but a layered system of defensive capabilities would mitigate the risk of swarms of drones or other attacks that may come from Iran," Dunford said.

Trump said earlier on Friday that he believed his military restraint so far showed "strength," as he instead imposed another round of economic sanctions on Tehran.

"Because the easiest thing I could do, 'OK, go ahead. Knock out 15 different major things in Iran.' ... But I'm not looking to do that if I can," Trump told reporters at the White House.