US allies in the Persian Gulf have loudly pushed for hawkish policies by Washington to pressure, isolate and cripple Iran, but this high-stakes strategy is now being put to the test by the unexpected US strike that killed Iran's most powerful military commander last week, thrusting the region closer to full-blown conflict.

Even as Gulf Arab states like Israel lobbied hard for tough US sanctions and maximum pressure on Iran, Saudi Arabia and the United Arab Emirates have wanted to avoid outright war.

Friday's airstrike that killed the Revolutionary Guard's powerful Quds Force commander, Qasem Soleimani, appears to have caught America's Gulf allies off-guard. Now they are trying to make sure the major escalation by President Donald Trump doesn't drag them further into the cross-hairs of rising tensions between Washington and Tehran.

Iran, which held an unprecedented multi-city funeral procession for Soleimani that drew millions to the streets to mourn him, retaliated early Wednesday by firing a series of ballistic missiles at two military bases in Iraq where American troops are stationed.

Read: 'We slapped Americans on the face,' says Iran Supreme Leader after strikes on US bases in Iraq

Trump signalled he would not retaliate militarily, but vowed to continue his campaign of maximum pressure and economic sanctions on Iran.

As the region braces for what comes next, Saudi Arabia and the UAE are calling for de-escalation.

Saudi Arabia dispatched Deputy Defence Minister Prince Khalid bin Salman to Washington, where he met with Trump and the US president's son-in-law and adviser Jared Kushner at the White House on Monday. The kingdom says he discussed “efforts to reduce tensions and avoid escalations that could further destabilise the region in light of the Iranian regime’s provocations and destabilising activities.”

Qatar’s foreign minister, meanwhile, travelled to Tehran the day after the killing of Soleimani and also called for de-escalation.

“Nobody wants the outbreak of conventional war because when conventional war happens there are no winners, there are just a series of losers,” said Mohammed Alyahya, the Saudi editor-in-chief of the Al-Arabiya English news website.

This latest round of tensions has pushed oil prices up, with Brent crude trading around $70 a barrel. UAE Energy Minister Suhail Al-Mazrouei said on Wednesday there is no risk at the moment to the movement of oil in the region or any shortages in oil supply.

He noted, however, that Soleimani’s killing was “definitely an escalation”.

“Iran is a neighbour. We are (geographically) very close to Iran and the last thing we want is another tension in the Middle East,” the energy minister said, reiterating calls for de-escalation.

'Let’s not let this go too far'

The UAE and Saudi Arabia have long wanted the US to push back Tehran’s drive to spread influence and power across the region, and Soleimani was central to Iran’s ambitions. Viewed by Sunni Muslims across much of the region as a menacing figure, his role as Quds Force commander put him in charge of lethal Shia proxy militias in Lebanon, Iraq, Syria and Yemen fighting against Gulf Arab interests. In Iran, he’s hailed as a national hero who defied US pressure.

Related: US knew about Iran missiles well before attacks: report

Even after Soleiman’s killing, there’s little indication they’ve stopped skirting the dangerous line between maximum pressure and war.

Alyahya said the pressure strategy is still needed to stop Iran’s Quds Force but he acknowledged that “it is a very risky game, and if it backfires, the consequences are grave.”

Robert Malley, who heads International Crisis Group and served on Obama’s National Security Council, said Gulf countries are likely satisfied that Soleimani was killed, but are also worried because Iran could inflict serious damage on their economies.

“I think they are now sending the message to the US and to others: ‘Let’s not let this go too far because you’re living very far away [...] we’re going to be the ones who will pay the price and you won’t be here to protect us’,” he said.

The Persian Gulf could be another target of Iranian retaliation. It hosts more than 30,000 US troops, including the Navy’s 5th Fleet stationed in Bahrain, US Army’s Central forward headquarters in Kuwait and at the sprawling Al-Udeid Air Base in Qatar. The US also has hundreds of troops in Saudi Arabia and advanced drones, F-35 fighter jets and several thousand military personnel in Al-Dhafra Air Base in Abu Dhabi.

Already over the summer, a series of attacks on oil tankers in the Persian Gulf and a major missile and drone attack on Saudi oil facilities were blamed on Iran. Tehran denied responsibility, though it did seize oil tankers around the crucial Strait of Hormuz, the narrow mouth of the Persian Gulf, through which 20 per cent of the world’s crude oil travels.

Over the weekend, the US warned American citizens in Saudi Arabia of a heightened risk of missile and drone strikes, particularly near military bases, oil and gas facilities and other critical civilian infrastructure.

'Is America ready for revenge?'

Since the September attack on Saudi Arabia, which temporarily halved its oil production, there appears to have been a quiet effort at diplomacy between Iran and the kingdom to ease tensions. But there’s no sign either side had inched closer to overcoming their rivalry.

Iraqi Prime Minister Adel Abdul-Mahdi told lawmakers in Baghdad on Sunday that he had been scheduled to meet Soleimani the morning he was killed. He said Soleimani was carrying a message from Iran’s supreme leader in response to a Saudi message relayed through Iraq to Iran about “important agreements and breakthroughs in Iraq and the region”. Neither Iran nor Saudi Arabia have confirmed Abdul-Mahdi’s comments.

Alyahya called Abdul-Mahdi’s account “an intricate tall tale”. Echoing widespread Saudi sentiment, he said Soleimani was no dove for peace.

US Secretary of State Mike Pompeo on Tuesday also dismissed the notion as “propagandist” and suggested that the Saudis share his view that Soleimani was not in Iraq on a peace mission.

Complicating the Gulf rulers’ calculations are questions about whether Trump’s decision to order the strike on Soleimani was made impulsively or is part of a longer-term strategy.

Gulf allies have been questioning Trump’s reliability as a security partner. Though he has strengthened America’s military presence in the Gulf amid rising tensions with Iran, Trump did not step in to militarily defend Saudi interests after the attack on oil sites and backed away from retaliation when Iran shot down a US surveillance drone in the Strait of Hormuz.

In remarks on Wednesday Trump stated: “We are independent, and we do not need Middle East oil” and said he would ask Nato to step up its involvement in the region.

“The constant thing about Trump is he’s unpredictable,” Emirati political analyst Abdulkhaleq Abdullah said. “We didn’t [know] that he would do this. Now, we don’t know what he will do next.”

“Is America ready for revenge of a sort coming from Iran? Is the region ready for a sharp escalation?” asked Abdullah.