Global airline stocks tumbled Monday, dropping in altitude following a weekend attack on two key Saudi Arabian oil facilities that pushed oil prices briefly to their highest since the 1991 Gulf War, prompting concern that jet-fuel costs are likely headed higher.

In Europe, Air France-KLM (AF) shares slid 4.6%, EasyJet (ESYJY)  shed 3.3%, and Airbus  (EADSY)  and Lufthansa (DLAKF) each fell 3% on Monday. In North America, Delta Air Lines (DAL - Get Report)  dropped more than 4% in early trading, falling $2.45 to $57.56, while shares of American Airlines (AAL)  dropped 4.54%, or $1.36, to $28.59. 

Shares of Southwest Airlines (LUV - Get Report)  dropped 0.79%, while United Continental (UAL - Get Report) fell 1.7% in early trading.

Oil prices jumped to their highest levels since May after Saturday's air drone attack on Saudi Arabian oil facilities disrupted global crude supplies, sparking concern of higher fuel costs.

Futures retreated slightly after President Donald Trump said he had authorized the use of oil from the country's emergency reserve. In a series of tweets, Trump said that he had ordered that oil from the Strategic Petroleum Reserve, or SPR, be used "if needed."

He said he would use enough oil "to keep the markets well-supplied."

Saudi Arabia oil supply was attacked. There is reason to believe that we know the culprit, are locked and loaded depending on verification, but are waiting to hear from the Kingdom as to who they believe was the cause of this attack, and under what terms we would proceed!

— Donald J. Trump (@realDonaldTrump) September 15, 2019

Airlines are heavily dependent on the price of oil, which dictates their fuel costs. Operators seek to hedge their costs by determining what they expect the average cost of fuel to be a year out and hedging that both in setting passenger ticket prices and calculating other costs.

Even so, Brent crude contracts for November delivery, the global benchmark, were up 9.2%, $5.56 higher from their Friday close in New York and trading at $65.78 a barrel in European trading after earlier surging to almost $72 a barrel -- a near-20% gain that marked the biggest single-day spike since the Gulf War in 1991.

Gasoline futures, meanwhile, were up about 9%.

In Asia, China's three biggest airline operators all dropped sharply in Hong Kong, with China Eastern Airlines dropping more than 4%, while China Southern Airlines and Air China each fell at least 2.5%. Cathay Pacific (CPCAY) , Hong Kong's flagship airline, fell 3.9%.