But it was not immediately clear if he was referring to fresh troop movements, or those reported in the media previously.
“Our Intelligence has informed us that the Chinese Government is moving troops to the Border with Hong Kong. Everyone should be calm and safe!” Trump said in a tweet.
Chinese state and social media had earlier aired video of security forces gathering across the border from the enclave, which has been rocked by unrest for more than two months.
The Global Times and the People’s Daily ran a minute-long video compiling clips of armoured personnel carriers and troop carriers purportedly driving to Shenzhen, which borders Hong Kong.
Hu Xijin, editor-in-chief of the state-run Global Times, said on social media that the military presence is a sign that if the situation in Hong Kong doesn’t improve, China will intervene.
Speaking to reporters in Morristown, New Jersey on Tuesday, Trump called the situation in Hong Kong “very tricky”.
“I hope it works out peacefully, nobody gets hurt, nobody gets killed,” he said.
Meanwhile, Washington said Beijing has denied requests for two American warships to make port visits to Hong Kong.
The USS Green Bay – an amphibious dock landing ship – had been scheduled to visit Hong Kong on August 17, and the guided missile cruiser USS Lake Erie was scheduled to visit in September.
Commander Nate Christensen, deputy spokesman for the US Pacific Fleet, said it was up to China to say why it denied the requests.
He said the US Navy expects port visits to Hong Kong to resume.
The last American warship to visit the SAR was the USS Blue Ridge in April 2019. (AP, AFP)