BANGKOK, March 4, (AP): Asian shares tumbled Wednesday, with South Korea's benchmark plunging more than 12%, 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.

"I think the Iran situation is getting out of hand, and I think that US President Donald Trump miscalculated enormously," said Francis Lun, CEO of Venturesmart Asia. "The situation is very grim." 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 12.1% to 5,093.54. Samsung's shares dropped 11.7%, while SK Hynix gave back 9.6%. 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 nearly 14%. 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 US President Donald Trump announced Tuesday that he had ordered the US 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 US 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.