Oil prices rose Thursday afternoon as escalating U.S.-Iran tensions heightened fears of supply disruptions in the Middle East. The U.S. launched a fresh wave of attacks on Iran on Wednesday, striking multiple targets on President Trump’s orders. U.S. forces targeted air-defense and radar sites near the Strait of Hormuz, a senior U.S. official said. The Strait of Hormuz is a critical waterway through which one-fifth of the world’s oil is transported.

The American military described the attacks as “additional self-defense strikes” in response to Iran’s “unwarranted and continued aggression,” marking the latest exchange of attacks between the two sides this week.

On Tuesday, the U.S. military launched three waves of attacks against Iranian radar sites, air-defense systems and ground-control stations after an Iranian drone downed a U.S. Apache helicopter in the Strait of Hormuz a day earlier.

“At this stage, it is too early to say whether the current escalation marks a full resumption of hostilities or a dangerous but still containable episode,” Rystad Energy’s Jorge Leon said in an email. “The direction of travel is now more uncertain, and the next few days will be critical in determining whether diplomacy can reassert itself or whether the conflict moves into a more sustained escalation cycle,” the senior vice president and head of geopolitical analysis added.

Front-month West Texas Intermediate crude oil futures rose 1.3% to $91.21 per barrel, while front-month Brent crude oil futures gained 1.2% to $94.20 a barrel, according to ICE data.

Equity markets across the Asia-Pacific region were broadly mixed Thursday afternoon after swinging between mild gains and losses earlier in the session.

“Geopolitical uncertainty continues to cloud the outlook after the U.S. launched strikes against Iran again as Trump claims that Iran has been dragging out talks whilst the latter has now said the [Strait of Hormuz] is shut,” said Maybank analysts. “The U.S. did say this morning that the latest strikes were done although sentiment is still fragile,” they added.

South Korea’s Kospi rose 0.7% after earlier slipping as much as 4.4%, and Japan’s Nikkei Stock Average edged 0.3% higher after earlier falling as much as 2.9%. Singapore’s FTSE Straits Times Index added 0.1%, while India’s Sensex shed 0.3%.