Washington, DC (CNN) — As the war with Iran continues, oil prices are soaring and airlines will see higher fuel costs – which could hit travelers around the world in their wallets.

It will “probably start quick,” United Airlines CEO Scott Kirby told CNBC last week.

Crude oil prices surged after the US and Israel’s strikes on Iran and hovered around $100 a barrel on Thursday, closing above $100 for the first time in nearly four years, before closing the week slightly lower at $99 a barrel.

The war has also had massive operational impacts on airlines in the region, with nearly 50,000 flights canceled since February 28, according to aviation analytics firm Cirium.

Rob Britton is an adjunct professor of marketing at Georgetown’s McDonough School of Business and a retired American Airlines executive. He said for now, the availability of petroleum has only been slightly disrupted, but oil prices have soared.

“If fuel prices remain high, fares will rise,” Britton told CNN. “There’s no mystery there … So just doing some simple math, one might expect ticket prices to rise almost proportionately.”

Second to labor, an airline’s largest cost is jet fuel. Dependent upon crude oil prices, it could be 20-30% of an airline’s total expenses, Britton said.

“Historically, airlines have been prompt at raising fares when fuel prices spike,” he said.

Yet, airlines often have trouble freely passing on cost increases, such as higher fuel prices, to passengers, even if it’s costs being felt widely across the industry, said Zach Griff, author of an airline newsletter, From the Tray Table.

“There’s so much more to flight prices than just the cost of fuel or even just the cost of operating a given flight,” he said.