A massive security operation gripped Hong Kong on Tuesday as authorities tried to prevent demonstrators from marring a visit by a senior Beijing official.

Zhang Dejiang, China's third-highest-ranking Communist Party official and chairman of the National People's Congress, is in town to attend an economic summit. He's the most senior statesman to visit from Beijing since the pro-democracy Umbrella Revolution in 2014, and his trip comes shortly after a series of apparent political kidnappings that have many Hong Kongers worrying that mainland China is seeking to exert more control over the semi-autonomous territory.

Even considering those tensions, Tuesday's heavy show of force still surprised Nash Jenkins, a Hong Kong-based correspondent for TIME.

"Hong Kong is China's freest city,” Jenkins says. “And for the first time, I saw the presence of security authorities prohibiting protesters from actually gathering in the streets."

"I don't think it's melodramatic to call it a police state,” he added. “I was not even allowed to enter the designated press zone. I saw student protesters shoved to the ground because they were not in the designated protest zones. The city had employed workers to glue pavement stones to the street to ensure they wouldn’t be thrown as weapons. It was very tense.”

Attitudes toward Beijing spark fierce debate in Hong Kong, where residents enjoys some legal freedoms denied to the mainland — most notably freedom of speech — under the "one country, two systems" framework. Many pro-democracy and pro-independence activists say their individual freedoms and Hong Kong's limited autonomy are under increasing threat from the mainland.

“Hong Kongers want Hong Kong to be independent,” says Jenkins, “because they see their socio-political identity as so fundamentally and existentially distinct from that of mainland China.”

Zhang's three-day visit is therefore a fraught event for many Hong Kongers, who see it as symbolic of this larger battle.

As for Zhang, his tone so far has been conciliatory. Upon arrival at Hong Kong International Airport he said he was willing to listen to “all sectors of society's suggestions and demands on how ... the country and Hong Kong should develop."

From PRI's The World ©2016 PRI