Oil prices surged Friday after US and UK forces launched strikes against Iran-backed Houthi rebels in Yemen following attacks on ships in the Red Sea, fuelling worries about a wider conflict in the crude-rich region.
The move weighed on sentiment among investors, though stocks were mixed after data showing US inflation rose more than expected last month further dented hopes for an early interest rate cut by the Federal Reserve.
The offensive against rebel positions in Yemen -- which included fighter jets and Tomahawk missiles -- fanned already high tensions in the Middle East as Israel presses on with a war in Gaza in response to a Hamas attack on the country in October.
The Houthis have carried out a growing number of strikes on the key international Red Sea route since the Gaza war erupted, hitting trade flows at a time when supply strains are putting upward pressure on inflation globally.
Washington and London's decision followed a Houthi bombardment this week that was said to be their heaviest to date, having carried out missions on an almost daily basis since the start of the Israel-Hamas war.
News of the US-UK strikes, which President Joe Biden said also had support from Australia, Bahrain, Canada and the Netherlands, sent oil prices up more than two percent Friday, with analysts saying WTI could pass $75 and Brent could top $80.
The jump in prices sparked concerns about a fresh spike in inflation that could complicate central bank pivots to a more dovish monetary policy this year, reviving worries about the economy.
"If oil were to substantially increase... that would jeopardise... this soft landing scenario that is quite likely for the year," Andrew Slimmon, of Morgan Stanley Investment Management, told Bloomberg Television.
Investor sentiment was further dampened by data showing the US consumer price index rose more than forecast in December, dealing another blow to the prospects of the Fed starting its rate cut cycle as soon as March.
Equities had finished 2023 with a strong rally on expectations the central bank would hit the ground running on cutting rates owing to falling inflation and an indication from decision-makers that they would do so this year.
But minutes from the Fed's December meeting showed officials were keen to keep borrowing costs elevated for an extended period to make sure they had a handle on prices. That was followed by forecast-busting jobs data that showed the labour market remained resilient.
While Thursday's closely watched CPI reading was not the nail in the coffin for a March reduction, observers said it made that argument harder to make.
Still, Chris Zaccarelli of the Independent Advisor Alliance said: "What should be most important for investors is that the Fed is done raising rates.
"Whether they cut in March or cut in June and whether they cut four times, three times, or only two times, shouldn't matter too much."
Wall Street's three main indexes ended flat, and Asia was mixed.
Hong Kong and Shanghai climbed after data showing another drop in Chinese consumer prices that fanned speculation the government will unveil fresh stimulus measures for the beleaguered economy.
There were also gains in Wellington, Manila and Jakarta, while Tokyo piled on more than one percent to extend a rally that on Thursday propelled it past 35,000 for the first time since 1990.
The Nikkei surge has been fuelled by a weaker yen, which boosts exporters, and optimism about the outlook for the Japanese economy.
Still, Sydney, Singapore, Seoul and Taipei were in the red.
West Texas Intermediate: UP 2.6 percent at $73.86 per barrel
Brent North Sea Crude: UP 2.4 percent at $79.30 per barrel
Tokyo - Nikkei 225: UP 1.1 percent at 35,422.95 (break)
Hong Kong - Hang Seng Index: UP 0.4 percent at 16,362.11
Shanghai - Composite: UP 0.6 percent at 2,902.49
Dollar/yen: DOWN at 145.02 yen from 145.29 yen on Thursday
Pound/dollar: UP at $1.2781 from $1.2770
Euro/dollar: UP at $1.0984 from $1.0969
New York - Dow: FLAT at 37,711.02 (close)
London - FTSE 100: DOWN 1.0 at 7,576.59 (close)