HAVANA -- (AP) -- Fidel Castro's government called the closure of a Russian spy base a ``grave threat'' to Cuban security and blamed the United States for pressuring Russia to close the facility, which has monitored U.S. military moves and communications for decades.

 The statements were made through the Cuba's Communist Party newspaper, Granma, on Thursday.

 The announcement to close the facility comes amid increased Russian cooperation with the United States and cooler relations with Cuba.

 Created in 1964 after the Cuban Missile Crisis, the radar facility in Lourdes, about 13 miles south of Havana, has remained an active example of Cuban-Soviet Cold War cooperation.

 Moscow says most of its Russian personnel will the leave the base by January but a closure date has not been announced. It also remains unclear what will happen to the base's intelligence equipment.

 Last year, the U.S. Congress voted to restrict aid to Russia unless it closed the Lourdes facility.