Cuba's Foreign Ministry on Saturday said U.S. claims that its troops were fighting in Ukraine were unfounded and released for the first time information on legal proceedings against Cubans for mercenary activity in the war in Eastern Europe.

Communist Cuba has openly sided with its ally Russia in the conflict in Ukraine while also calling for peace talks.

Reports of Cubans on the battlefield first surfaced in 2023, resulting in an investigation in Cuba. Havana later stated that these Cubans were mercenaries.

"In the period from 2023 to 2025, nine criminal proceedings have been presented to the Cuban courts for the crime of mercenarism, against 40 defendants," Saturday's statement said.

"Trials have been held in eight cases, of which five resulted in convictions against 26 defendants, with sentences ranging from five to 14 years' imprisonment. Three processes are pending the Court's ruling, and one case is pending trial," the foreign ministry said in the statement.

The United Nations is preparing to vote this month on a nonbinding resolution calling on Washington to lift its decades-long embargo on Cuba. The resolution has been passed in the General Assembly with wide margins year after year since 1992.

The General Assembly adopted the resolution last year, with 187 countries voting in favor. The U.S. and Israel were the only countries that voted against it, while Moldova abstained.

A U.S. State Department cable to diplomatic missions lobbying against the resolution states that Cuban soldiers are fighting alongside Russia in Ukraine.

"After North Korea, Cuba is the largest contributor of foreign troops to Russia's aggression, with an estimated 1,000-5,000 Cubans fighting in Ukraine," said the cable, which was first reported by Reuters on Monday.

The Cuban foreign ministry statement said, "Cuba is not part of the armed conflict in Ukraine, nor does it participate with military personnel there, or in any other country."

The ministry admitted it did not know how many nationals were involved on either side of the conflict, but said it had "a practice of zero tolerance for mercenarism, trafficking in persons and the participation of its nationals in any armed confrontation in another country."