BANGKOK (AP) — Asian shares tumbled Wednesday, with South Korea’s benchmark plunging more than 11%, while oil prices climbed even higher as the war with Iran widened.

Worries over Iran have hammered most world markets, spooking investors who fear more spikes for oil prices may grind down the global economy and sap corporate profits.

South Korea’s Kospi led the regional losses as energy security concerns vanquished optimism over the boost computer chipmakers like Samsung Electronics and SK Hynix have been getting from expanding use of artificial intelligence.

The Kospi sank 11.5% to 5,127.28. Samsung’s shares dropped 9.1%, while SK Hynix gave back 6.5%.

The Korea Exchange temporarily halted trading for the Kospi index, while a circuit breaker was also triggered on the tech-oriented Kosdaq after it fell by more than 8%. It later dropped 12%.

South Korea’s stock market has been one of the world’s best performers this year, but its economy depends heavily on trade and fuel imports, that are threatened with disruptions to traffic through the Strait of Hormuz, the narrow gateway to the Persian Gulf through which roughly a fifth of globally traded oil passes.

The rise in oil prices appeared to moderate after U.S. President Donald Trump announced Tuesday that he had ordered the U.S. Development Finance Corp. to provide political risk insurance and guarantees for financial security of all maritime trade.

“If necessary, the United States Navy will begin escorting tankers through the Strait of Hormuz, as soon as possible,” Trump said in a message posted by the White House on X.

The price of U.S. benchmark crude oil climbed 1.3% to $75.53 per barrel. Brent crude, the international standard, gained 1.7% to $82.74 per barrel. Its price has jumped more than 13% since the war began.

“Trump’s assurances of the US underwrite shipping insurance against Middle East conflict risks and even U.S. naval escorts only mitigate, but do not eliminate, enduring upside risks to oil prices,” Mizuho Bank said in a commentary.

The increased insurance costs filtering through to shipping would ultimately cost an extra $5 to $15 a barrel.

It said that “evolving Middle East risks, entailing escalating attacks, means that the ‘war premium’ remains firmly intact.”

In Tokyo, the Nikkei 225 shed 3.9% to 54,059.47. Like South Korea and Taiwan, Japan depends heavily on imports of oil and natural gas from the Persian Gulf.

Elsewhere in Asia, the Hang Seng in Hong Kong fell 2.9% to 25,023.18 and the Shanghai Composite index shed 1.2% to 4,074.22.

In Australia, the S&P/ASX 200 declined 1.9% to 8,901.20.

Taiwan’s Taiex lost 4.4% and shares in Bangkok sank 8%.

On Tuesday, the S&P 500 finished with a loss of 0.9%, at 6,816.63, after dropping as much as 2.5% on concerns over the war’s damage to the economy. The Dow Jones Industrial Average pared its loss to 0.8%, closing at 48,501.27.

The Nasdaq composite fell 1% to 22,516.69.

In the bond market, Treasury yields leaped in the morning with worries about inflation. The yield on the 10-year Treasury briefly rose above 4.10% before pulling back just below 4.06%. It was at 4.05% late Monday and just 3.97% on Friday.

Higher yields can make it more expensive for U.S. households and businesses to borrow money, affecting everything from mortgages to bond issuances. They also put downward pressure on prices for stocks and all kinds of other investments.

Some analysts say stocks could rebound if the war doesn’t last that long. But they acknowledge it could take a while for that to become clear, and Tuesday’s swings for markets showed how uncertain things are.

The more evident impact has been on the average price of a gallon of gasoline. Drivers in Europe and some Asian cities waited in line to fill their tanks with fuel.

While the U.S. does not face a shortage as a net oil exporter, prices are influenced by global market trends.

In the U.S., a gallon of regular was selling for $3.11 on average, up 11 cents, according to motor club AAA, surprising some drivers at the pump. Gasoline prices were already rising before the U.S. launched strikes on Iran as refiners were switching over to summer blends of fuel.

The war could have broader implications.

Higher inflation partly due to the war could tie the Federal Reserve’s hands and keep it from cutting interest rates. The Fed lowered rates several times last year and indicated more cuts were to come in 2026. That would help boost the economy and job market, but lower rates can also worsen inflation.

In other dealings, the dollar fell to 157.61 Japanese yen from 157.74 yen. The euro slipped to $1.1592 from $1.1612.

The price of gold rose 0.9%, while silver gained 1.5%.

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Associated Press writer Kim Tong-hyung in Seoul, South Korea, contributed.

Elaine Kurtenbach, The Associated Press