Jet fuel prices have risen by 60% to $3.40 per gallon, according to the Argus U.S. Jet Fuel Index. This comes after the Iran conflict disrupted the world's most critical energy shipping route, the Strait of Hormuz. The cost of fueling one Boeing 737-800 for a domestic route surged by nearly $10,000 in a single week. Airlines are now warning that fare increases will likely occur quickly. Fuel is an airline's second-largest expense after labor, accounting for between 20% and 30% of all annual operating costs across the global aviation industry. Airlines across Asia, Europe, and Oceania have already announced fare hikes or added new fuel surcharges on tickets. The International Air Transport Association reported that global jet fuel prices had risen approximately 83% over the past month.