A teenager who says he's a US permanent resident and his fiancée are once again on the run from the threat of extradition to their homeland, China, in a sign of Beijing's lengthening reach over perceived dissidents abroad.

Chinese officials had sought Wang Jingyu, a 19-year-old student, over his online comments about deadly border clashes between Chinese and Indian forces last year. He was arrested by plainclothes police in Dubai while transferring for a flight to the US in early April and was held for weeks, in a case that the US Department of State has described as a human rights concern. He said Chinese authorities in Dubai took away his green card.

Wang was freed May 27, just hours after The Associated Press asked about him. He fled first to Turkey and then to Ukraine, as a temporary safe place that was open to Chinese passport holders without COVID-19 entry restrictions.

But on Thursday, the AP has learned, Wang received a warning via email that Chinese officials knew he was hiding in Ukraine, and had escalated the charges against him to subversion of state power, a vaguely defined charge often used by Chinese authorities to imprison critics. The email claimed to be from the state security department of Chongqing city police, which has said they are looking for him.

“Your actions have completely changed from the simple charge of picking quarrels and stirring up trouble and demeaning our border martyrs to subversion of state power,” the email read. “We in the public security organs and national security organs know exactly where you are. I want to remind you that China and Ukraine have an extradition agreement.”

On Monday, Wang received another email from the same person, saying they had prepared measures if the couple fled again. The AP has seen screenshots of both emails.

“I was really scared, I couldn't sleep well at night,” Wang said. “It was very clear from what they said that they would take action against me.”

Terrified, Wang and his fiancee, Wu Huan, 26, flew to the Netherlands, which does not have an extradition treaty with China. They are seeking asylum or at least a temporary stay visa.

Upon arrival at the Amsterdam airport, the couple was informed by Dutch immigration authorities that their passports had been cancelled, said Bob Fu, president of ChinaAid, who helped organise their escape from Ukraine.

Bas Belder, a former member of the European Parliament, said he has been in contact with the Dutch Justice Ministry to bring the couple's plight to the minister's attention. He added that the case, including the cancellation of their passports, highlights “genuinely criminal behaviour of the Chinese party state to pursue their citizens even beyond Chinese territory and try by all possible means to capture them.” The Justice Ministry said it could not comment on individual cases.

Chinese authorities did not respond to multiple requests for comment, to the Ministry of Foreign Affairs, Chongqing police and the Chinese embassy in Washington.

The US State Department declined to comment on Tuesday. It had acknowledged Wang's arrest in Dubai and told the AP it was “alarmed by human rights violations and abuses in China.”

The case feeds into growing fears of extraterritorial reach on China's part, especially with concerns that Hong Kong's national security law, passed last year, could apply to people of any nationality even outside Hong Kong.

Formal extradition requests are far from the only tool China uses to exercise control over its citizens abroad, said Jerome Cohen, an adjunct senior fellow at the Council for Foreign Relations and an expert on Chinese law. More common are informal attempts, used by the US as well, relying on deportations by foreign countries that are rarely made public and are much harder to track, he said.

“It's obvious this is a blatant effort to extend Chinese power abroad,” Cohen said of the case. “There is certainly increasing long-arm attempts by China by one means or another — informal deportation, extradition…, coercion against their families in China, using every technique in the book, legal and illegal.”

Wang has been fleeing from Chinese police and travelling with Wu abroad since July 2019, after he posted comments in support of mass demonstrations in Hong Kong on a Chinese social media website. His parents sent him abroad to wait out any potential trouble.

In February this year, China announced that it had lost four soldiers months ago in a brutal fight between Chinese and Indian forces in a border dispute in the Karakoram mountains. Wang questioned why the Chinese government had waited so long to announce the death toll and became a target of state media.

Six others were detained by police for their remarks about the Chinese-India border conflict this year, according to a report by the state-owned Global Times in February, based on local police statements. Wang was the only one of the seven abroad and out of reach. Chongqing police then said in a public statement that they were on the hunt for him for the all-encompassing charge of “picking quarrels and stirring up trouble,” often wielded against political targets.

The People's Daily, the official paper of the Communist Party, started a hashtag, “Man staying abroad who slandered frontier heroes is now being hunted down online” on the social media platform Weibo. It has since been viewed 280 million times, and Wang said he has gotten threatening phone calls.

After Wang's comments in February, his parents were detained by Chongqing police, he said. He gave interviews to Voice of America, Radio Free Asia and DW in Chinese to publicise what was happening to them.

He has been unable to reach his parents independently since. The Chongqing police sent him a recording of his father warning him not to take interviews with US media outlets, which the AP has heard.

Authorities in Dubai did not respond to requests for comment Tuesday. A Dubai Public Prosecution charge sheet obtained by the AP after his arrest there described Wang as facing an investigation over allegedly “insulting one of the monotheistic religions,” a charge typically referring to insulting Islam. When shown the charge sheet, the Dubai Media Office said charges were dropped and Wang was let free.

“Chinese authorities have not inquired about Mr. Wang, nor did they request his deportation to China, nor has there been any contract between UAE and Chinese authorities with regards to Mr. Wang,” the Dubai Media Office said at the time.

Wu flew to Dubai in April shortly after her fiance was arrested. She hired a lawyer, while posting on social media and giving interviews to raise awareness about his case.

On May 27, Wu was abducted from her hotel in Dubai, the couple said. Guo Baosheng, a Chinese dissident who also runs a Youtube channel and had publicised Wang's detention by UAE authorities, said he urged Wu to get out of the hotel right before she disappeared.

Wu said she was brought to a Dubai police station and interviewed by officials from the Chinese consulate. She was then taken into custody of Chinese officials, according to the couple. She went on a hunger strike for several days and her mental condition was close to collapse, so she was released on June 8, she said.

“This is a particularly painful recollection,” she said. “I don't have a lot of political viewpoints. I really, really love China….I never thought I would experience this injustice in UAE.”

In the meantime, Wang is still posting criticism of the Chinese government on Twitter. He said he will continue to speak out in any way he can.

“I want to make my voice heard within the firewall through every possible method,” he said. “I still feel that only when the real Chinese people inside the firewall wake up, only then will the country have hope.”