Crude oil prices were up by around 3% during Friday’s trading start as rising tensions in the Middle East threaten secure crude supply from the region.

International benchmark Brent crude was trading at $68.18 per barrel at 0615 GMT with a 2.83% increase after closing Thursday at $66.30 a barrel.

American benchmark West Texas Intermediate was at $62.91 a barrel at the same time with a 2.88% gain after ending the previous session at $61.15 per barrel.

The U.S. confirmed Thursday that it carried out a strike that killed Qasem Soleimani, the commander of the Iranian Revolutionary Guards Corps’ Quds Force, in the Iraqi capital Baghdad.

The Pentagon accused Soleimani of planning to carry out attacks on U.S. diplomats and service members in Iraq and the region, saying the slain leader was responsible for the deaths of hundreds of American and coalition service members.

Iranian Foreign Minister Javad Zarif harshly reacted to the killing of Solaimani.

“The US bears responsibility for all consequences of its rogue adventurism,” Zarif wrote on Twitter.

The Middle East is home to almost half of the world’s proved oil reserves and accounts for one-third of global oil production.

Read more: Oil prices up 3% with tensions in Middle East