The United States advised airlines on Saturday that its Caribbean airspace curbs would expire at midnight ET (8am Cyprus time) and flights could resume as schedules are quickly updated, Transportation Secretary Sean Duffy said.

The comments on social media followed the cancelation of hundreds of flights by major airlines after the US attack on Venezuela and the capture of its president, Nicolas Maduro.

Key carriers United Airlines, American Airlines, and Delta were readying to resume flights to the Caribbean by Sunday.

In a statement, United said a flight to San Juan in Puerto Rico was planned for Saturday night, adding, “We expect to operate most scheduled flights to the region for Sunday.”

Delta Air Lines expects to fly its normal Carribean schedule on Sunday, it said in a statement, but adjusted to reposition resources.

American Airlines said in a statement that it was preparing for the Eastern Caribbean airspace to reopen Sunday and had added more than 3,700 extra seats to and from the region on top of resuming scheduled service.

It said it was operating extra flights and deploying larger aircraft, including widebodies, to “add as much lift as possible” to help customers affected by the FAA‑mandated closure.

Even after the removal of curbs, however, airlines will need several days to restore normal operations, said airline analyst Robert Mann, adding, “They have a day’s worth of passengers basically,” already stranded in the Caribbean.

American Airlines, Delta, United, Frontier Airlines, Spirit Airlines and JetBlue Airways began cancelling flights, in line with Federal Aviation Administration airspace closures in the Caribbean.

JetBlue canceled 215 flights, an airline spokesperson said.

In a notice to airmen, the FAA said it closed the airspace to US carriers “due to safety-of-flight risks associated with ongoing military activity.”

In other security notices for non-US air carriers, the agency warned them away from Venezuelan airspace.

It cautioned British operators against “potential risk from anti-aircraft weaponry and heightened military activity” if flying within 160 kilometres of Venezuelan airspace.

The FAA declined further comment.

NON-US AIRLINES ALSO CANCEL FLIGHTS

Several European and South American airlines also cancelled flights.

The curbs would be lifted “when appropriate,” Duffy had said in a post on social media.

American military activity near Venezuela led to a near mid-air crash in November between a JetBlue airliner and a US aerial refueling tanker, media said.

Several carriers waived change fees and fare differences for customers affected by the closures if they postponed travel.

Saturday’s US military operation captured Venezuela’s long-serving President Nicolas Maduro, President Donald Trump said, promising to put the country under American control for now, by deploying U.S. forces if necessary.

Air Canada said its Caribbean and South American operations were normal, under guidance from Transport Canada, and it was monitoring the situation, adding, “We will update as required if the situation changes.”

Commercial air traffic over Venezuelan airspace appeared to stop after Saturday’s attack, records on tracker FlightRadar24 showed.