TOKYO, March 23, 2026 (BSS/AFP) - Benchmark US oil contract WTI was up Monday after US President Donald Trump gave Iran a 48-hour ultimatum to open the Strait of Hormuz or face decimation of its energy infrastructure and Israel warned the war would continue for several more weeks.

At 0015 GMT, the price of West Texas Intermediate (WTI) was up 0.44 percent to $98.66 per barrel. It had climbed to just over $100 a barrel earlier Monday.

South Korea's benchmark Kospi index and Japan's Nikkei sharply dropped in early trade.

The Kospi was down 4.69 percent at 5,509.88 points. The Nikkei 225 was down 3.54 percent at 51,483.91 points.

The price of North Sea Brent crude, the global market benchmark, was down 0.02 at $112.17 per barrel.

On February 27, the day before the US-Israeli attacks began on Iran, WTI had stood at $67.02 and Brent was at $72.48 per barrel.

Trump and Tehran have issued tit-for-tat threats as the war entered its fourth week, with the US president demanding the Islamic republic reopen the blocked Strait of Hormuz, through which around 20 percent of the world's oil and gas shipments transit.

The bottleneck has nearly halted all petroleum shipments through the narrow waterway, and oil prices have spiked.

Trump posted late Saturday on Truth Social that US forces would "hit and obliterate" Iranian power plants -- "starting with the biggest one first" -- if Tehran did not fully reopen the strait within 48 hours, or 23:44 GMT on Monday, according to the time of his post.

In response, Iran's army said it will target energy and desalination infrastructure "belonging to the US and the regime in the region," according to the Fars news agency.

Meanwhile Israel's military chief, Lieutenant General Eyal Zamir, said Sunday his forces were expanding their ground campaign against Iran-backed Hezbollah in Lebanon, and warned of a lengthy operation.

"We are now preparing to advance the targeted ground operations and strikes according to an organised plan," he said.

In retaliation for the US and Israeli military operation, Iran is carrying out missile and drone strikes against infrastructure -- particularly energy targets -- as well as against ships in the Gulf, specifically threatening those venturing into the strait.