On Thursday, Mexico’s navy announced it had launched a search-and-rescue mission in the Caribbean Sea to find two sailboats carrying humanitarian aid to Cuba. The vessels had not arrived in Havana as planned, raising concerns for their safety.

According to the navy’s statement, the two boats set sail from Isla Mujeres in Quintana Roo, Mexico, last week. They were headed for Havana, carrying nine crew members of various nationalities.

Although the sailboats were expected to reach their destination between March 24 and 25, they have neither communicated their status nor confirmed their arrival, prompting the navy to take action.

The missing sailboats are part of a larger grassroots effort aimed at providing much-needed assistance to Cuba, which is grappling with severe power shortages and an escalating economic crisis. This situation has been exacerbated by the U.S. tightening its embargo on oil and other goods. Notably, another vessel from the convoy successfully docked in Havana on Tuesday.

Last week, volunteers in Mexico loaded the boats with essential items such as rice, baby wipes, beans, baby formula, and medicine. This initiative, known as the “Nuestra America Convoy,” is a non-governmental effort to supply food, medicine, and energy-related goods to the island nation.

“The captains and crews are seasoned sailors, and both vessels are outfitted with the necessary safety systems and signaling equipment,” a convoy spokesperson told Reuters. “We are working closely with the authorities and have confidence in the crews’ ability to safely reach Havana.”

Mexico also established contact with maritime rescue coordination centers in Poland, France, Cuba and the United States, as well as diplomatic representatives of the countries of origin of those on board, the navy said.