United States President Donald Trump has approved sending American troops to bolster Saudi Arabia’s air and missile defences after the largest-ever attack on the kingdom’s oil facilities, which Washington has squarely blamed on Iran. The Pentagon said the deployment would involve a moderate number of troops – 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 United Arab Emirates. The United States is also considering keeping an aircraft carrier in the region indefinitely.“In response to the kingdom’s request, the president has approved the deployment of US forces, which will be defensive in nature and primarily focused on air and missile defence,” US Defence Secretary Mark Esper said at a news briefing. “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.” The Pentagon’s announcement appeared to close the door to any imminent decision to wage retaliatory strikes against Iran following the attack, which rattled global markets and exposed major gaps in Saudi Arabia’s air defences.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, ‘Okay, 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. Meanwhile, the Revolutionary Guard warned on Saturday that any country that attacks Iran would become the “main battlefield”, after Washington ordered reinforcements to the Gulf following attacks on Saudi oil installations it blames on Tehran.Tensions escalated between arch-foes Iran and the US after last weekend’s attacks on Saudi energy giant Aramco’s Abqaiq processing plant and Khurais oilfield halved the kingdom’s oil output. Yemen’s Huthi rebels have claimed responsibility for the strikes but the US says it has concluded the attacks involved cruise missiles from Iran and amounted to “an act of war”.But Islamic Revolutionary Guard Corps Commander Major General Hossein Salami said Iran was “ready for any type of scenario”. “Whoever wants their land to become the main battlefield, go ahead,” he told a news conference in Tehran. “We will never allow any war to encroach upon Iran’s territory.” “We hope that they don’t make a strategic mistake”, he said, listing past US military “adventures” against Iran.Salami was speaking at Tehran’s Islamic Revolution and Holy Defence museum during the unveiling of an exhibition of what Iran says are US and other drones captured in its territory. It featured a badly damaged drone with US military markings said to be an RQ-4 Global Hawk that Iran downed in June, as well as an RQ-170 Sentinel captured in 2011 and still intact.The Guards also displayed the domestically manufactured Khordad 3 air defence battery they say was used to shoot down the Global Hawk.“What are your drones doing in our airspace? We will shoot them down, shoot anything that encroaches on our airspace,” said Salami, noting Iran had defeated “America’s technological dominance” in air defence and drone manufacture. His remarks came only days after strikes on Saudi oil facilities claimed by Yemen’s Huthis, but the US says it has concluded the attack involved cruise missiles from Iran and amounted to “an act of war”.Saudi Arabia, which has been bogged down in a five-year war across its southern border in Yemen, has said Iran “unquestionably sponsored” the attacks. The kingdom says the weapons used in the attacks were Iranian-made, but it stopped short of directly blaming its regional rival.“Sometimes they talk of military options,” Salami said, apparently referring to the Americans. Yet he warned that “a limited aggression will not remain limited” as Iran was determined to respond and would “not rest until the aggressor’s collapse”. The Guards’ aerospace commander said the US ought to learn from its past failures and abandon its hostile rhetoric. “We’ve stood tall for the past 40 years and if the enemy makes a mistake, it will certainly receive a crushing response,” Brigadier General Amirali Hajizadeh said.The US upped the ante on Friday by announcing new sanctions against Iran’s central bank, with US President Donald Trump calling the measures the toughest America has ever imposed on another country.