HONG KONG — Tony Chung, a young activist who called for Hong Kong’s independence from China, was sentenced to three years and seven months in prison Tuesday after pleading guilty to secession activity under the city’s far-reaching national security law.

His crime involved no violence, only slogans, Facebook posts and speech. The judge said Chung had played an active role as an organizer and added “fuel to the flames” of the secession effort.

“Secession need not involve actual violence,” Judge Stanley Chan said. “The sentence needs to deter future acts.”

The penalty underlined the draconian nature of the security law, which was drafted by Beijing and took effect in June 2020. The law effectively created a parallel legal system without the safeguards offered by Hong Kong’s common-law framework, such as trial by jury or the right to bail. Speech deemed to undermine the Chinese state can lead to life in prison — even though Hong Kong’s mini-constitution is supposed to protect freedom of expression.

Chung, 20, who was a teenager at the time of his offenses, is the youngest person to be imprisoned under the security law and the third in total. Two men sentenced previously under its provisions, Tong Ying-kit, 24, and Ma Chun-man, 31, were also punished for slogans deemed a threat to the state.

Chung received a slightly reduced sentence for pleading guilty. Eric Lai, a Hong Kong law fellow at Georgetown University’s Center for Asian Law, said the security law creates a legal environment in which defendants feel pressure to plead guilty rather than defend themselves.

“The governments should ask themselves whether criminalizing young people with draconian laws can really win back public trust toward the court or the government,” Lai said.

Chung was a student activist who became involved in politics in high school. He co-founded the group Studentlocalism, which advocated in schools for Hong Kong’s independence. The group terminated its operations just before the national security law came into force. Officials said at the time that the law would not be used retroactively; Chung was among the first to be arrested under the security law weeks later.

“I plead guilty. I have no shame in my heart,” Chung said in court this month.

Hong Kong independence has always been a red line for China, which resumed sovereignty over the former British colony in 1997. Beijing has argued that pro-independence sentiment must be stamped out in Hong Kong, but the cause has never enjoyed majority support in the city, even among pro-democracy activists.

In an interview with a local publication in 2017, Chung explained his stance.

“We often see the situation in China — it’s exactly why we do not want the place we live to become the same as China,” he said.

While out on bail in October last year, Chung tried to seek asylum at the U.S. Consulate in Hong Kong. He was apprehended by several men before he could reach the consulate’s gates. It is rare, but not unprecedented, for the United States to grant noncitizens protection or asylum at its diplomatic compounds. He had been detained without bail since then.

Prosecutors argued that Chung’s actions dating back as early as 2016, before the security law was enacted, were relevant because he continued to violate the law after it took effect. They pointed to the manifesto of Studentlocalism, arguing that it expressed intent to “separate the country” and sold hoodies featuring the words “Hong Kong independence.”

As evidence of his guilt, prosecutors also pointed to Chung’s comments thanking then-U.S. Secretary of State Mike Pompeo for certifying that the United States could no longer consider Hong Kong autonomous.

Chung also pleaded guilty to money laundering for using public donations to promote his pro-independence organization.

In a white shirt and pants, Chung calmly nodded to spectators who waved at him from the public gallery, before he was led away.

Chung was sentenced last year to four months in prison for desecrating the Chinese flag and taking part in an unlawful protest in 2019.