SINGAPORE/LONDON: Oil climbed above US$100 a barrel on September 9 for the first time in six weeks as escalating attacks involving U.S. and Iranian forces added to concerns over Middle East supplies after months of export disruptions and falling inventories.

Brent, the global oil benchmark, has gained about 25 percent since early last month as hopes have faded for a permanent resolution to the six-month-old U.S.-Iran conflict.

The rally accelerated this week after Iran-backed Houthi attacks on Saudi energy facilities set oil installations ablaze, raising the risk of wider disruptions across the Gulf.

"Oil investors are expressing their view about the impact of the latest bout of escalation in the Middle East in an unambiguous way," said Tamas Varga, of oil broker PVM. "They are voting with their dollar, and this vote strongly indicates that unless the Strait of Hormuz re-opens, and oil starts flowing again uninterruptedly, supply will not be aligned with demand in the foreseeable future."

Brent remains below the $126 a barrel level reached earlier in the conflict. However, a sustained period above $100 could increase transport and manufacturing costs, revive inflation concerns and keep interest rates higher for longer.

Six months of reduced Middle East oil exports because of the war in Iran have depleted stocks in some major consuming countries.

The United States has drawn heavily on its Strategic Petroleum Reserve, which now holds 289.7 million barrels, its lowest level since 1982. The decline follows years of releases under former President Joe Biden and President Donald Trump aimed at cushioning consumers from high fuel prices.

High pump prices pose a risk for Trump's Republican Party ahead of November's midterm elections, when it will seek to retain narrow majorities in both houses of Congress. The U.S. national average gasoline price was expected to reach $4.03 a gallon over the Labor Day weekend, while analysts consider $4 a gallon a pain point for many consumers.

The International Energy Agency announced a 400-million-barrel release from emergency oil reserves in March, about three quarters of which has been released. The agency says the global economy still has substantial stocks.

Total global oil inventories, including commercial supplies, the U.S. reserve, Chinese stocks and oil on water, remain fairly comfortable according to the IEA. However, some supplies are in transit, already committed to buyers or held in countries such as China that provide limited public information about available reserves.

Global oil stocks fell below 7.9 billion barrels in July from a 2026 peak of nearly 8.3 billion in February.

Around 10 million barrels per day of oil exports, equivalent to roughly 10 percent of world demand, remain missing because of the Iran war, according to estimates from oil-shipment tracker Vortexa.

While producers including the United States, Canada and Guyana have increased output, the IEA said last month it expected global oil supply to decline this year by 4.3 million barrels per day, or about four percent.

With emergency stockpiles depleted and millions of barrels of daily supply already offline, analysts say the market has less capacity to withstand further disruptions than at the beginning of the war.

"I think the market is trying to treat this rise in energy prices as a one-off. It's not. This is structural. It's not going away, and it's part of what I would argue as a security premium. And it's only going to get bigger," said Jeffrey Currie, co-chairman at Abaxx Markets.