Oil prices jumped again on Tuesday after fresh United States strikes against Iran that marked a new escalation in hostilities that has fuelled fears over their already fragile truce and the chances of another spike in inflation.

However, tech firms enjoyed a much-needed reprieve after the latest bout of selling, although they only managed to claw back some of the hefty losses fuelled by growing fears over the AI boom.

The latest attacks came after Iranian forces struck a commercial ship in the Strait of Hormuz, through which about a fifth of global oil passes, early on Sunday, before announcing the closure of the waterway.

That led to a series of US strikes on sites in the Islamic republic, which replied by hitting targets in Bahrain, Jordan, Kuwait and Oman.

United States President Donald Trump told conservative radio host Hugh Hewitt on Monday before the latest US attacks that “we’re going to hit them very hard tonight, and we’re going to hit them hard tomorrow”.

He later declared on Truth Social that the United States would be “known as ‘THE GUARDIAN OF THE HORMUZ STRAIT'” and levy a 20 per cent fee on all cargo shipped through the waterway.

While Iran’s ports would again be blockaded, Trump said “all other countries will have fair and open use of the strait”.

However, he also said a deal with Tehran to end the crisis was still possible.

“Yeah, I think a deal is possible. Sure, I do,” he told reporters in the Oval Office.

“We had a deal with them two days ago and then they said ‘Oh we can’t make that deal. We have to negotiate it further.'”

Oil prices shot up more than nine per cent on Monday over fears of renewed conflict and the possibility that a fresh surge in inflation could force the Federal Reserve and other central banks to hike interest rates soon.

They continued to rise on Tuesday, piling on more than one per cent.

“With Trump, one never quite knows how seriously to take such pronouncements, but Gulf allies would not be pleased with this plan, and it almost certainly violates international law,” said BNZ’s Jason Wong.

“The 20 per cent levy would add about $16 to the cost of every barrel of oil passing through the strait on a typical supertanker.”

“It remains to be seen whether the plan will stick, probably not, and whether it is merely a negotiating tactic aimed at getting Iran to pause its military strikes on shipping in the area.”

Equity markets mostly rose after seeing through the day, though confidence remains fragile as traders worry that the sector’s AI-led rally has gone too far.

Seoul was again at the forefront of the action, ending in positive territory after wild swings that saw it drop as much as five per cent at one point.

SK hynix ended up more than three per cent, the day after a 15 per cent collapse.

Its New York-listed shares, which soared more than 13 per cent on their debut on Friday, plunged more than nine per cent on Monday.

Rival Samsung was up 3.3 per cent.

Tokyo, Hong Kong, Shanghai, Singapore, Manila and Jakarta were also up, though Wellington, Taipei, Mumbai and Bangkok fell.

London, Paris and Frankfurt opened lower.

Investors are looking ahead to a big week, with earnings season about to kick off, Fed boss Kevin Warsh due to testify in Congress and US inflation data set to be released.

Meanwhile, Fed governor Christopher Waller stoked concerns over an early interest rate hike as inflation remains elevated.

“If we get another hot reading on core inflation this week, then the rate-setting committee will need to consider tightening monetary policy in the near term,” he said on Monday.

Key figures around 0715 GMT showed West Texas Intermediate up 2.6 per cent at $80.15 a barrel, and Brent North Sea Crude up 2.4 per cent at $85.37 a barrel.

Tokyo’s Nikkei 225 closed up 0.7 per cent at 67,743.50, while Seoul’s Kospi closed up 0.7 per cent at 6,856.83.

Hong Kong’s Hang Seng Index was up 0.6 per cent at 24,352.92, and Shanghai’s Composite closed up 1.4 per cent at 3,967.13.

London’s FTSE 100 was down 0.3 per cent at 10,464.94.

The euro traded up against the dollar at $1.1389 from $1.1384 on Monday, while the pound was up at $1.3358 from $1.3353.

The dollar was down against the yen at 162.34 yen from 162.43 yen, while the euro was up against the pound at 85.27 pence from 85.25 pence.

New York’s Dow closed down 0.3 per cent at 52,498.64.