The Pentagon on Friday announced it will deploy additional US troops and missile defense equipment to Saudi Arabia and the United Arab Emirates, as Donald Trump has at least for now put off any immediate military strike on Iran in response to the attack on the Saudi oil industry.

The US defense secretary, Mark Esper, told Pentagon reporters this is a first step to beef up security and he would not rule out additional moves down the road. General Joseph Dunford, the chairman of the Joint Chiefs of Staff, said more details about the deployment will be determined in the coming days, but it would not involve thousands of US troops.

Other officials said the US deployment would probably be in the hundreds and the defensive equipment heading to the Middle East would probably include Patriot missile batteries and possibly enhanced radars.

The announcement reflected Trump’s comments earlier in the day when he told reporters that showing restraint “shows far more strength” than launching military strikes and he wanted to avoid an all-out war with Iran, which has denied responsibility for the attack.

Instead, he laid out new sanctions on the Iranian central bank.

“I think the strong person’s approach and the thing that does show strength would be showing a little bit of restraint,” Trump told reporters during a meeting with the Australian prime minister, Scott Morrison. “Much easier to do it the other way, and Iran knows that if they misbehave, they are on borrowed time.”

Dunford told reporters the extra equipment and troops would give Saudi Arabia a better chance of defending against unconventional aerial attacks.

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

The US has not provided any hard evidence that Iran was responsible for the attacks, while insisting the investigation continues, but Esper on Friday said the drones and cruise missiles used in the attack were produced by Iran.

“The attack on 14 September against Saudi Arabian oil facilities represents a dramatic escalation of Iranian aggression,” Esper said, adding that the US has thus far shown “great restraint”.

Iran has denied involvement and warned the US that any attack will spark an “all-out war” with immediate retaliation from Tehran.

In deciding against an immediate US strike, Trump for the second time in recent months pulled back from a major military action against Iran that many Pentagon and other advisers fear could trigger a new Middle East war. In June, after Iran shot down an American surveillance drone, Trump initially endorsed a retaliatory military strike then abruptly called it off because he said it would have killed dozens of Iranians.

On Friday, he left the door open a bit for a later military response, saying people thought he would attack Iran “within two seconds”, but he has “plenty of time”.