Iran issues ‘battlefield’ warning as US deploys troops

Any country that attacks Iran will become the "main battlefield", the Revolutionary Guards warned on Saturday 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 United States 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".

Washington approved the deployment of troops to Saudi Arabia at "the kingdom's request", Defence Secretary Mark Esper said, noting the forces would be "defensive in nature" and focused on air and missile defence.

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.

In Riyadh, the Saudi minister of state for foreign affairs, Adel al-Jubeir, warned of "appropriate measures" once the source of the strikes on its oil facilities was confirmed.

"We have asked the United Nations to do an investigation and there are also other countries involved in the probe," he told a press conference.

"We are sure the attack was not launched from Yemen, but from the north.

"When it (the probe) is completed, we will take the appropriate procedures to deal with this aggression," said Jubeir, without specifying.

Iran's Salami, for his part, 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.

His remarks came only days after the 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 has 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 United States upped the ante on Friday by announcing new sanctions against Iran's central bank, with President Donald Trump calling the measures the toughest America has ever imposed on another country.

Washington has imposed a series of sanctions against Tehran since unilaterally pulling out of a landmark 2015 nuclear deal in May last year.

It already maintains sweeping sanctions on Iran's central bank, but the US Treasury said Friday's designation was over the regulator's work in funding "terrorism".

Also on Saturday, Iran denied its oil infrastructure had been successfully attacked by a cyber operation, after reports of disruptions to the sector online.

"Contrary to Western media claims, investigations done today show no successful cyber attack was made on the country's oil installations and other crucial infrastructure," the government's cyber security office said.

The statement did not specify which reports it was addressing.