Canadian airlines on Monday suspended flights to Cuba, which warned it was running out of jet fuel, as the US tightens its grip on the communist-run nation’s oil supply by blocking shipments from Venezuela.

Air Canada, the country’s biggest carrier, said in a statement that aviation fuel is not projected to be commercially available at airports as of Tuesday, as governments issue notices warning that the supply is likely to be unreliable.

Smaller rivals WestJet and Air Transat also cancelled flights due to anticipated fuel shortages.

The shortfall is set to last from February 10 through March 11, according to a notice to pilots published late on Sunday.

It comes just two days after Cuban officials said air travel would not initially be impacted by a fuel rationing plan announced on Friday.

The Cuban Aviation Corporation (ECNA) published a short statement on Monday morning, just hours after the notice to pilots was issued, but made no mention of the fuel shortage or flight cancellations.

“We continue working tirelessly to ensure the safety, fluidity, and order of the airspace, supporting airline operations and ensuring that aviation in Cuba maintains the levels of reliability that characterise us,” ECNA said.

The Cuban government did not immediately respond to a request for comment.

REFUELING STOPS

Due to the fuel restrictions announced by the Cuban authorities, Spanish carrier Air Europa said it would make a refuelling stop at Santo Domingo Airport in the Dominican Republic as part of its Madrid–Havana–Madrid operation starting on Tuesday.

Fuel shortfalls are not new to Cuba, which has long struggled with supply issues, and many airlines already have plans in place to deal with them.

Similar crises have prompted many carriers to refuel in nearby third countries, including Panama, the Bahamas, the Dominican Republic and the US.

Montreal-based Air Canada said over the coming days it will send empty flights to pick up and fly home about 3,000 customers in Cuba.

It said it will fly in with extra fuel for the return journey and make refuelling stops if necessary.

WestJet said on its website that it had begun an orderly wind-down of its Cuban operations effective on Monday, also including some flights to assist customers with returning to Canada.

Air Transat said it suspended all flights to Cuba until the end of April and was organising repatriation flights to bring its customers back to Canada.

In Cuba, travellers and their families said they were unnerved by the recent announcements.

“Today it’s one thing, and tomorrow it’s another,” said Cuban Benigno Gonzalez, who was at Havana’s Jose Marti International Airport on Monday morning to drop off his daughter for a flight to Mexico. “This will hurt everyone who travels.”

An early morning Copa Airlines flight to Panama departed on time from Havana on Monday, and several American Airlines flights were slated to arrive later in the day, airport officials confirmed to Reuters.

U.S. carriers American Airlines, Southwest Airlines and Delta Air Lines, which fly to Cuba from nearby Florida, said they are continuing to fly to the country and are not currently experiencing any impact on their operations.

The carriers said aircraft operating flights to Cuba carry sufficient fuel for their next trips.

VENEZUELA IMPORT PROBLEM

Cuba has historically relied on Venezuela to provide much of its jet fuel, but the Caribbean island nation has not received any crude or refined products from its top ally since mid-December, when the U.S. moved to block the South American nation’s exports.

US President Donald Trump has since vowed Cuba would receive no more oil from Venezuela and has threatened to slap tariffs on any nation sending fuel to Cuba, effectively cutting off the island’s supply of aviation gas.

Venezuela’s state oil company PDVSA in December loaded an 80,000-barrel cargo of jet fuel for Cuba, but the tanker never left amid a strict US blockade on the OPEC country.

The vessel, which has moved Venezuelan fuel to Cuba since last year, last week discharged the jet fuel at a PDVSA-operated port and loaded some 150,000 barrels of gasoline, according to the company’s shipping schedules.

The boat had yet to set sail on Monday, according to ship monitoring services. Its intended destination was not immediately clear.