Cuban and U.S. officials have been investigating a deadly confrontation in Cuban waters that a week’s worth of competing claims has turned into a diplomatic flashpoint.

Cuban authorities said Cuban soldiers confronted a speedboat as it approached an island and opened fire on the troops, who fired back, according to the Cuban government. Cuba’s Ministry of the Interior said the boat was carrying 10 people and that the exchange left four dead and six wounded, and Cuban officials said the wounded were detained.

Cuba’s government said the passengers included Cubans living in the United States and accused them of trying to infiltrate the country to carry out terrorism. The Ministry of the Interior said it launched an investigation, and the foreign minister said that Cuba is carrying out follow-up work on the case.

In Washington, U.S. Secretary of State Marco Rubio said the American government was gathering information about the incident, including whether the people aboard the boat were U.S. citizens or permanent residents, and he said it was not a U.S. government operation. The U.S. Attorney’s Office for the Southern District of Florida said it was pursuing answers “through every legal and diplomatic channel available,” indicating parallel inquiry efforts by U.S. law-enforcement authorities.

Cuba’s President Miguel Díaz-Canel used social media to say Cuba “does not attack or threaten,” and he wrote that Cuba would defend itself with determination and firmness against what he described as terrorist or mercenary aggression aimed at undermining its sovereignty and national stability. Cuban foreign minister statements also referenced what Cuba called “numerous terrorist and aggressive infiltrations” from the United States since 1959.

Cuban authorities identified seven of the 10 passengers and said two of them, Amijail Sánchez González and Leordan Enrique Cruz Gómez, were wanted based on their alleged involvement in the promotion, planning, organization, financing, support or commission of terrorism. The government also identified the other passengers as Conrado Galindo Sariol, José Manuel Rodríguez Castelló, Cristian Ernesto Acosta Guevara and Roberto Álvarez Ávila.

The Cuban government said it had found assault rifles, handguns, homemade explosives, bulletproof vests, telescopic sights and camouflage uniforms during the search of the Florida-registered speedboat. The Associated Press said it was unable to verify those details because boat registrations are not public in Florida. The AP also reported that Cuba had earlier misidentified one passenger but later corrected the name after saying it had erred.

Cuban officials said one of the four killed was Michel Ortega Casanova, and his brother, Misael Ortega Casanova, told the Associated Press that Michel had developed what he described as an “obsessive and diabolical” quest for Cuba’s freedom after the family’s suffering on the island before moving to the United States. The AP reported that Misael Ortega Casanova said his brother was an American citizen who had lived in the U.S. for more than 20 years.

The AP said another passenger, Galindo Sariol, was identified as a former political prisoner in a 2025 interview with Martí Noticias, a U.S.-based news site that has long called for a change of government in Cuba. Cuban officials also said the confrontation involved a Florida-registered speedboat and detained the wounded before identifying the passengers.

While exchanges between Cuba’s coast guard and U.S.-flagged speedboats are not uncommon, deaths from such confrontations are rare, according to the AP. The story traced historical examples involving Cuban exiles, including the failed Bay of Pigs Invasion in April 1961 and the Feb. 24, 1996 incident in which Cuba’s air force shot down two unarmed civilian airplanes operated by Brothers to the Rescue, killing four.

As the investigations proceeded, the incident also raised questions about how it could affect U.S.-Cuba relations as tensions remain elevated, particularly after changes under President Donald Trump’s administration. The Associated Press reported that the U.S. halted oil shipments to Cuba that had been helping sustain the island, then signed an executive order on Jan. 29 that would impose a tariff on any country that sells or provides oil to Cuba, and the AP said experts warned the episode could lead to additional sanctions.

William LeoGrande, an American University expert on Cuba, told journalists during an online briefing that there was a risk the Trump administration “uses this incident as some kind of an excuse to come up with even more sanctions.” He also said that even if Cuba’s government presented captured weapons and sought to obtain confessions about what the passengers were trying to do, the underlying humanitarian impact of Cuba’s energy and economic crisis was unlikely to be resolved quickly.

The Associated Press said the U.S. Treasury Department had slightly eased restrictions on the sale of Venezuelan oil to Cuba on Wednesday. Even with that change, LeoGrande said Cuba’s private sector would not import enough oil “to really make a significant dent in the humanitarian crisis,” placing the focus back on the wider political and economic fallout alongside the immediate maritime investigation.