BUENOS AIRES šC On a balmy January night, an Argentine coast guard ship¡¯s radio ?picked up garbled Mandarin broadcast from nearby boats.

They were among some 200 Chinese fishing vessels that spend months at a time each year near the South American country¡¯s waters, hunting primarily for catch to feed the world¡¯s largest squid market.

The size of the flotilla has increased by nearly 50% over the last decade. In that time, Buenos Aires has bulked up its surveillance to ensure the fleet doesn¡¯t fish in the exclusive economic zone where Argentina controls all maritime resources.

But fears of overfishing just outside the country¡¯s waters remain, as do suspicions of intelligence gathering that were also shared by Washington, according to interviews with four Argentine and four U.S. former and current officials. Washington¡¯s efforts to spotlight global overfishing by Chinese-flagged vessels date back to the late 2010s, as the first Donald Trump administration began to emphasize U.S. strategic rivalry with Beijing. Trump, who ?last year extended a $20 billion economic lifeline to Argentine leader Javier Milei¡¯s government, has since declared U.S. ¡°dominance¡°?over the Western Hemisphere to be a key objective of his administration.

That has set Washington at odds with China, which has over the last 20 years invested ?heavily in ?Latin America, including Argentina. Beijing has developed Venezuela¡¯s oil sector, built Brazilian and Peruvian port facilities and set up a military-run space-observation station in Argentina that has drawn U.S. scrutiny.

China¡¯s Foreign Ministry said??in response to questions that the suspicions of intelligence gathering around the fishing fleet were ¡°pure speculation, lacking any factual basis.¡±

¡°China is a responsible fishing nation, strictly enforcing the regulation of its distant-water fishing activities and engaging in mutually beneficial fisheries cooperation with relevant countries in accordance with international law,¡± the ministry said.

The U.S. has helped Argentina better patrol its waters to protect against illegal fishing, including approving its purchase of U.S.-origin P-3C Orion maritime surveillance aircraft.

Argentina has had suspicions that some Chinese fishing boats were equipped with antennas that are inconsistent with fishing activities, ?said Marcelo Rozas Garay, who served as vice minister of defense in 2025.

¡°We think what they were looking for in reality was information or intercepting communication,¡± he said, without providing details about the antennas.

Buenos Aires and Washington have also discussed Chinese vessels that Argentina observed moving in ways which ?indicate that they could be mapping the continental shelf for undersea resources, said Juan Battaleme, the defense secretary for international affairs under Milei until December 2025.

Under international law, only Argentina can explore and exploit resources on its shelf.

Washington was concerned that China is using its fleet to build a regional presence and test Argentina¡¯s ability to...