(Reuters)

Tens of thousands of Hong Kong residents marched through the streets in defense of their cherished freedoms Saturday, in the face of what many see as a growing threat from mainland China exactly two decades after the handover from British rule. 

Earlier in the day, China’s president, Xi Jinping, marked the 20th anniversary of the handover with his sternest warning yet to the territory’s people: You can have autonomy, but don’t do anything that challenges the authority of the central government or undermines national sovereignty.

Under the terms of the 1997 handover, China promised to grant Hong Kong a high degree of autonomy for at least 50 years, but Xi said it was important to have a “correct understanding” of the relationship between one country and two systems.

“One country is like the roots of a tree,” he told Hong Kong’s elite after swearing in the territory’s new governing chief executive, Carrie Lam. “For a tree to grow and flourish, its roots must run deep and strong. The concept of one country, two systems was advanced first and foremost to realize and uphold national sovereignty.”

Many in Hong Kong accused China of violating the territory’s autonomy in 2015 by seizing five publishers who were putting out gossipy books about the Chinese leadership and allegedly distributing them on the mainland. 

Some are also angry that Beijing intervened to disqualify newly elected pro-independence lawmakers who failed to correctly administer the oath of office last year. Many are worried about a steady erosion of press freedom, and that China is increasingly determined to call the shots in a range of areas.

But Xi made it clear that challenges to Beijing’s authority would not be allowed.

“Any attempt to endanger China’s sovereignty and security, challenge the power of the central government and the authority of the Basic Law of the Hong Kong Special Administrative Region, or use Hong Kong for infiltration or sabotage activities against the mainland, is an act that crosses the red line and is absolutely impermissible,” he said.

That message didn’t appear to go down well on the streets of Hong Kong.

“He’s threatening Hong Kong’s people, saying he has the power to make us do what he wants,” said Anson Woo, a 19-year-old student. “But I still have hope. Seeing all the people around me today, the people of Hong Kong are still fighting for what we value.”

Organizers said 66,000 people joined Saturday’s annual march, which they said was meant to deliver a message to the Chinese president. Researchers from Hong Kong University, however, estimated the crowd at between 27,000 and 35,000, the South China Morning Post reported.

Organizers had hoped to bring out 100,000 people, and although they blamed rain and aggressive policing for the lower turnout, a more likely explanation is fatigue — the failure of the 2014 democracy protests led many to conclude that taking to the streets won’t wring concessions from China.

“Young people have a sense of powerlessness, and hence the apathy,” said Patrick Chiu, a 20-year-old student. “Some young people even see their way out as making money and leaving Hong Kong at some point.”

A poll by the Chinese University of Hong Kong showed people here attach greater importance to judicial independence and freedom of the press than to economic development. Any notion that Hong Kong as a city is only about making money is clearly not accurate.

“We have to take the chance to express our views while we still can,” said Chan Sui Yan, a 15-year-old schoolgirl. “They say it is one country, two systems, but right now we are losing a lot of the rights we value.”

Some protesters chanted slogans demanding democracy, criticizing the territory’s ruling elite or the Communist Party. Many called for the release of Nobel laureate and democracy icon Liu Xiabo, imprisoned in China since 2008, who was taken to a hospital last week under close guard for treatment for advanced liver cancer.“We want to show the mainland there are other voices, outside the official voice,” said teacher Tong Siu, 53. “We want to safeguard the core values of Hong Kong.”

In his speech, China’s leader said that the concept of one country, two systems was a great success and should be implemented “unswervingly” and not be “bent or distorted.” While his words made it clear that sovereignty took precedence over autonomy, he said neither aspect should be neglected. “Only in this way will the ship of one country, two systems break the waves, sail steadily and last the distance,” he said.

Yet many people here say China challenged Hong Kong’s autonomy again in March with Lam’s election as chief executive. The former bureaucrat, who trailed well behind rival candidate John Tsang in opinion polls, was chosen by a panel of 1,200 members of the territory’s elite that was packed with pro-Beijing loyalists. Although Tsang was also an establishment figure, political experts say Beijing seemed to want someone in the chief executive’s chair who would not challenge its authority.

At the swearing-in ceremony Saturday, Xi also did not shy away from raising two demands that have previously brought Hong Kong residents out on the streets in the hundreds of thousands. Xi said the territory needed to improve its systems “to defend national security, sovereignty and development interests,” as well as “enhance education and raise public awareness of the history and culture of the Chinese nation.”

China’s demand that Hong Kong pass a national security law prompted massive street protests 14 years ago, while plans to implement a program of “patriotic education” brought more people onto the streets in 2012 and helped politicize the territory’s youths.

Both plans were subsequently shelved, but Lam has indicated that she wants to put them back on the table. She also argues that the time isn’t right to satisfy a popular demand for greater democracy by allowing a future chief executive to be chosen by universal suffrage.

Marchers said moves to interfere with the education system smacked of “brainwashing.”

Martin Lee, Hong Kong’s veteran pro-democracy political leader, said China was deliberately confusing patriotism with obedience. 

“When they say you must love the country, what they mean is you must obey the Communist Party,” he said. “We have no problem with the Communist Party as long as it adheres to the promises made to us.”

But Lee said China had not fulfilled its promise to grant Hong Kong greater democracy. “They kept on postponing democracy,” he said. “That’s why young people are losing their patience.”

On Saturday morning, a small group of pro-democracy protesters said they were attacked by hired thugs when they tried to hold a demonstration, and then were briefly detained and beaten by police.

Joshua Wong, who led protests against patriotic education in 2012 and in favor of democracy in 2014, was among the group and called the incident another violation of the promise to maintain Hong Kong’s values, including the right to free speech. “‘One country, two systems’ has given way to ‘one country, one-and-a-half systems,’” he told The Washington Post.

“Why would Hong Kong people want to accept patriotic education from a country that is ruled by a single party dictatorship?” he said. “This is the core question. If the government is not elected by the people, how can we have a sense of belonging?”

Luna Lin contributed to this report.