Blinken says warned Chinese leaders about Cuba

"Yes, I made very clear we would have deep concerns about PRC (People's Republic of China) intelligence or military activities in Cuba," the top US diplomat told reporters in London after visiting Beijing.

"This is something we're going to be monitoring very, very closely, and we've been very clear about that," he added.

"And we will protect our homeland, we will protect our interests."

Blinken met President Xi Jinping and Chinese foreign-policy chiefs during his two-day visit, with both sides talking up limited progress from the highest-level US trip to China in nearly five years.

Notable strains include the spread of Chinese influence much closer to US shores under Xi.

Washington officials say China has set up intelligence operations in Cuba, just off the southeastern US coast.

And earlier Tuesday, the Wall Street Journal reported that China and Cuba are negotiating to establish a new joint military training facility on the island.

Nevertheless, Blinken stressed that it remained better to talk to China and noted the "long relationship" between Xi and President Joe Biden.

"It would be irresponsible not to engage, irresponsible because it makes more likely the possibility of misunderstandings, miscalculations, and thus conflict," he said.