China to Build Station That Could Spy on U.S. from Cuba, Officials Say

China is planning to build a facility in Cuba that U.S. officials are concerned could be capable of spying on the United States by intercepting electronic signals from nearby U.S. military and commercial facilities, according to three U.S. officials familiar with the agreement.

Beijing has built listening outposts elsewhere and has a military presence in Cuba, but an eavesdropping station could give China a foothold about 100 miles from the Florida coastline, from which it could potentially conduct surveillance operations against the United States.

The proximity of the planned facility to the United States is particularly concerning, officials said, because it could amplify Beijing’s technological capacity to monitor sensitive operations across the Southeastern states, including several military bases.

“We are deeply disturbed by reports that Havana and Beijing are working together to target the United States and our people,” Senators Mark Warner, Democrat of Virginia, and Marco Rubio, Republican of Florida, who lead the Senate’s Intelligence Committee, said in a joint statement on Thursday. “The United States must respond to China’s ongoing and brazen attacks on our nation’s security.”

The details of China’s and Cuba’s negotiations — which U.S. officials described on the condition of anonymity to discuss sensitive intelligence — come as the Biden administration has attempted to stabilize relations with Beijing, its main strategic rival, after a period of rising tensions. The Wall Street Journal first reported on plans to build a facility in Cuba.

President Biden’s National Security Council pushed back against reports of the planned facility. “This report is not accurate,” John Kirby, the council spokesman, said in a statement, declining to go into further detail. “We have had real concerns about China’s relationship with Cuba, and we have been concerned since Day 1 of the administration about China’s activities in our hemisphere and around the world.”

Mr. Kirby said that the administration was closely monitoring those activities and taking steps to counter them. He added that “we remain confident that we are able to meet all our security commitments at home and in the region.”

Several diplomatic, military and climate engagements between the two countries were frozen last year after former Speaker Nancy Pelosi’s visit to Taiwan. Bilateral relations had a further setback earlier this year when a Chinese spy balloon was caught traversing the United States, hovering near sensitive military sites.

The incident inspired a backlash from Congress and prompted Antony J. Blinken, the secretary of state, to cancel a scheduled trip to Beijing in February. Mr. Blinken plans to make the trip soon, according to U.S. officials, after weeks of intense diplomacy that included a meeting between Jake Sullivan, the national security adviser, and a senior Chinese official, Wang Yi. It is unclear if the latest revelations about the planned facility in Cuba could affect the visit once again.

Representatives for the Central Intelligence Agency and the Office of the Director of National Intelligence declined to comment.

Carlos Fernández de Cossio, a foreign ministry official in Cuba, said that reports of plans to build a Chinese spy base in the country were “totally false and unfounded.” A representative for the Chinese embassy said Beijing was “not aware of the case.”

China and the United States routinely conduct surveillance operations on one another. The United States sends surveillance flights over the South China Sea, deploys military assets in allied host nations around the Pacific and sells and supplies arms to Taiwan, a democratic island that the Chinese government considers part of its territory.

American officials have accused China in recent years of ambitious hacking attacks against the U.S. government and corporations, trying to recruit agents and assets inside and outside the United States and monitoring and threatening Chinese dissenters overseas.

That Beijing appears to be pursuing a closer arrangement with Cuba is not itself surprising, analysts say. The two countries have forged increasingly close ties since the end of the Cold War. China is Cuba’s largest trading partner, and plays a role in the island’s agricultural, pharmaceutical, telecommunications and infrastructural industries. Beijing also owns a significant measure of Havana’s foreign debt.

Cuba’s proximity to the United States has long made it a desirable strategic foothold for U.S. adversaries, perhaps most famously during the Cuban Missile Crisis, when the Soviet Union made and then backed down from plans to place nuclear missiles on the island nation. Today, the United States has a largely inimical relationship with Cuba, which, like China, is controlled by a Communist government.

Diplomatic relations between the United States and Cuba were put on ice shortly after Fidel Castro’s Communist regime came to power in 1959; the relations were only fully restored during President Barack Obama’s tenure. President Donald J. Trump reversed part of that move by reinstating certain travel bans to Cuba and re-designating the country as a state sponsor of terrorism.

Cuban officials have asked the Biden administration to lift this designation but it has remained in place. Still, Mr. Biden has relaxed some of Mr. Trump’s other restrictions. Cuba also continues to treat the U.S. base at Guantánamo Bay, which was established in the early 20th century, as an illegal occupation.