LONDON, United Kingdom (AFP) — Oil prices surged to US$100 a barrel on Thursday as Tehran-backed Houthi rebels targeted Red Sea shipping and United States (US) President Donald Trump threatened to strike them in return.

International benchmark oil contract Brent North Sea soared more than six per cent to hit the symbolic US$100 level, as the attacks potentially opened a new front in the Middle East war and Trump threatened the Houthis with “major military punishment”.

Iran meanwhile vowed to continue striking the Gulf region so long as it remains under attack from US strikes.

Saudi Arabia had been using the Red Sea to export millions of barrels of oil that normally flowed through the Strait of Hormuz, so the closure of that shipping channel would remove more oil from the market.

There are “no signs of a peace deal emerging as the US and Iran start to dig in and fears rise about choke points for certain fuel supplies”, noted Neil Wilson, UK investor strategist at Saxo.

“Investors are in a wary mood… as fresh jitters of worry about the ongoing energy crunch hit sentiment,” said Susannah Streeter, chief investment strategist at Wealth Club.

“With both the Strait of Hormuz and the Red Sea now under increasing pressure, markets are bracing for the possibility that the conflict could disrupt key energy routes (and) keep oil prices elevated,” she added.

The prospect of higher oil prices also raises the prospect of higher inflation and interest-rate hikes, adding to weak sentiment, analysts said.

European Central Bank head Christine Lagarde said some of its policymakers had considered raising rates at their meeting on Thursday, although all eventually voted to hold rates.

Wall Street’s main stock indices all fell more than one per cent at the start of trading.

“That isn’t surprising given what is going on with Alphabet, Tesla and the mega-cap stocks, oil prices and bond yields,” said Briefing.com analyst Patrick O’Hare.

The tech-heavy Nasdaq Composite fell 1.8 per cent.

“The scope of losses at the index level, though, doesn’t seem proportional to the gravity of the primary headlines,” he added, pointing to other companies receiving a boost after reporting earnings as well as reassuring US unemployment claims data.

All of the so-called Magnificent Seven tech stocks were lower.

Shares in Alphabet fell 6.0 per cent, with some investors taking fright that it raised its AI capital expenditure estimate for the full year to as much as US$205 billion, far more than expected.

Shares in Tesla slumped 9.6 per cent after the firm reported weaker-than-expected profits and a doubling of capital expenditures from the same quarter in 2025.

Investors’ appetite for all things AI has been tested in recent months on concern about elevated valuations and as they question when the trillions pumped into the sector will see returns.

Next week’s results from Microsoft, Meta and Amazon will be pored over for their capital spending plans.

Most Asian stock markets were buoyed by a much-needed bounce for regional tech firms.

European markets were weaker in afternoon trading.

The dollar firmed against its main rivals.

Eyes are on Tokyo after the yen hit a fresh four-decade low against the dollar amid concerns over the gap between the Bank of Japan’s low interest rates and those in the United States and other big economies.

Rising oil prices and concerns over Japan’s economy have added to pressure on the currency.

– Key figures around 1100 GMT –

Brent North Sea Crude: UP 5.7 per cent at US$99.42 per barrel

West Texas Intermediate: UP 4.5 per cent at US$90.75 a barrel

New York – Dow: DOWN 1.2 per cent at 51,613.11 points

New York – S&P 500: DOWN 1.2 per cent at 7,412.95

New York – Nasdaq Composite: DOWN 1.8 per cent at 25,237.60

London – FTSE 100: DOWN 0.9 per cent at 10,699.82

Paris – CAC 40: DOWN 1.8 per cent at 8,288.98

Frankfurt – DAX: DOWN 1.5 per cent at 24,768.13

Tokyo – Nikkei 225: UP 0.5 per cent at 66,422.60 (close)

Hong Kong – Hang Seng Index: UP 1.3 per cent at 25,210.81 (close)

Shanghai – Composite: UP 0.3 per cent at 3,876.78 (close)

Euro/dollar: DOWN at US$1.1381 from US$1.1411 on Wednesday

Pound/dollar: DOWN at US$1.3336 from US$1.3372

Euro/pound: UP at 85.33 pence from 85.33 pence

Dollar/yen: UP at 163.77 yen from 163.15