In its heyday, the Soviet signals intelligence base at Lourdes enabled Moscow to listen in on microwave transmissions of telephone conversations in the southeastern United States, keep an eye on the United States Navy in the Atlantic, monitor the space program at Cape Canaveral and communicate with its spies on American soil. In 1993, when Mr. Castro was chief of the Cuban armed forces, he boasted that Russia obtained 75 percent of its strategic intelligence on the United States through Lourdes.

The facility includes a large array of satellite dishes and antennas spread over about 28 square miles, about 150 miles from the Florida coast. The Kommersant report said that a decade of booming oil revenue meant that Russia could once again afford to operate Lourdes, and that deteriorating relations with the United States prompted a desire to reopen a peephole on a “potential enemy.”

When he was in Havana, Mr. Putin spoke publicly of a revival of military and technological cooperation with Cuba but gave no specifics.