As Russian citizens traveling to Cuba are “evacuated”, Russia will only operate return flights from Cuba.

Moscow aviation authorities said Russia was preparing to evacuate its citizens heading to Cuba. US imposes oil blockade The island nation has cut off supplies of aviation fuel.

“Due to difficulties refueling Cuban aircraft, Aeroflot and Nordstrom were forced to adjust their flight schedules to Cuban airports,” Russia’s federal aviation regulator Rosaviatsia said in a statement on Wednesday.

“Aeroflot will operate only some return flights to Moscow from Havana and Varadero to ensure the evacuation of Russian tourists currently in Cuba,” the regulator said.

The Russian Association of Tour Operators said earlier this week that there could be around 5,000 Russian tourists on the island.

Russia’s Economic Development Ministry separately called on citizens not to travel to Cuba, which is experiencing its worst fuel crisis in years. U.S. cuts off oil supplies Venezuelan President Nicolás Maduro returned from Venezuela after the U.S. military kidnapped him in early January.

Russia’s TASS news agency reported that the Russian embassy in Havana was in contact with national carrier Aeroflot and Cuban aviation authorities to “ensure the safe return of our citizens.”

TASS said Aeroflot had announced repatriation flights for Russians and reported that the embassy in Havana told Russian media outlet Izvestia that Moscow planned to deliver humanitarian aid to Cuba, including oil and petroleum products.

Cuba’s humanitarian ‘collapse’

Moscow, a traditional ally of Havana, accuses Washington of trying to “Suffocating” Caribbean Island Countries.

Kremlin spokesman Dmitry Peskov said on Monday that Moscow was discussing “possible solutions” to provide Havana with “all assistance” it needs.

It is reported that more than 130,000 Russians will visit Cuba by 2025, making them the third largest group of tourists after Canadians and Cubans living abroad.

Air Canada, Air Transat and WestJet have also Cutting flights to Cuba due to fuel shortage.

While Cuba has been in a deep economic crisis for years, caused largely by longstanding U.S. sanctions stemming from Washington’s antipathy toward Havana’s socialist leadership, the situation has become more dire since President Donald Trump returned to the White House.

Trump has directly threatened the Cuban government and recently passed an executive order allowing trade tariffs to be imposed on countries that supply oil to Cuba.

Cuba can only produce a third of its total fuel needs, and the country has experienced widespread power outages due to a lack of fuel. Bus and train services have been cut, some hotels have been closed, schools and universities have been restricted and public sector workers are working a four-day week.

U.N. Secretary-General Antonio Guterres warned last week that Cuba’s humanitarianism will “collapse” if its energy needs are not met.