Scan the pro-democracy demonstrations roiling Hong Kong this summer, and you will likely spot a few American flags flapping in the teargas-laden air.

“We want the U.S. to guard our rights,” a flag waver who gave his name as Joe said this month, explaining why he was carrying the Stars and Stripes. He wore a green surgical mask and a blue head scarf to obscure his identity, plus goggles to protect against police tear gas and projectiles. He declined to give his full name out of fear of arrest and retribution.

Hong Kong’s protesters are actively soliciting U.S. support. One reason: they believe the threat of consequences from the world’s largest economy will make Chinese President Xi Jinping think twice about deploying China’s military to quash the unrest.

A string of statements out of Washington in recent days has bolstered their cause.

On Sunday, President Trump warned the U.S. would have a hard time doing a trade deal with China if Hong Kong became “another Tiananmen,” a reference to the Chinese military’s 1989 massacre of pro-democracy students massed in Beijing’s huge central square.