The U.S. government has ordered airlines to reduce flights by 10 percent at 40 major airports amid safety concerns from an unprecedented 36-day government shutdown, Reuters.

Transportation Secretary Sean Duffy said the Federal Aviation Administration’s (FAA) decision followed a confidential safety review showing strain among unpaid air traffic controllers. The measure, expected to begin with smaller reductions over the coming days, aims to ease pressure on a workforce already operating with mandatory overtime and staffing shortages.

The flight cuts could affect more than 1,800 flights and 268,000 seats, primarily at the country’s busiest airports, including New York, Washington D.C., Chicago, Atlanta, Los Angeles, and Dallas. International routes are expected to be exempt.

Major U.S. carriers, including United, American, and Southwest Airlines, have begun adjusting their schedules and offering flexible refund policies. Airline shares fell roughly one percent in after-hours trading following the announcement.

The shutdown—now the longest in U.S. history—has left 13,000 air traffic controllers and 50,000 Transportation Security Administration agents working without pay, with around 750,000 federal employees furloughed. Industry groups and unions warned that the disruptions could soon translate into a broader economic hit if the political impasse continues.