Thomas J. Shattuck is an assistant editor and research associate at the Foreign Policy Research Institute.

On March 19, Taiwanese human rights and democracy activist Lee Ming-che traveled to China and has not been heard from since. It took China 10 days to confirm that Lee was, in fact, being detained for “endangering national security,” but he has yet to be formally charged. At least one Taiwanese person is detained in China for various political reasons every year, but this incident marks the first time a Taiwanese human rights activist has been arrested in China.

Lee’s detention is ominous because it will only serve to worsen the already tense relationship between Taiwan and China. The Trump administration has so far been conspicuously silent on the issue.

Lee, who regularly travels to China, never made it to his hotel. He had discussed Taiwan’s democratization on WeChat, a popular Chinese messaging app, has worked with human rights lawyers within China and even mailed books on Taiwan’s democracy to China. Indeed, he was almost begging for attention, knowing full well that the Chinese Communist Party censors such information from its citizens.

Over the past several years, China has passed notoriously vague laws, particularly the National Security Law and the Overseas NGO Management Law, limiting what nongovernmental organizations and activists are able to do insides its borders. It is difficult for people and organizations to know when they have broken one of these laws precisely due to their ambiguity.

The Taiwanese government’s muted response early on caused widespread disappointment. “If promoting universal human rights and democratic values is right, the government’s response to this kind of disappearance should not just be to warn NGO workers going to China to be more careful,” said Chiu E-ling, secretary general of the Taiwan Association for Human Rights.

Taiwanese President Tsai Ing-wen made no mention of Lee’s detention until April 12. Her office, not Tsai herself, said that she was “deeply concerned” and that “the government’s responsibility is to protect respect for the country and to protect the physical safety of citizens as well as their rights.” Her government and relevant agencies have contacted their Chinese counterparts several times to no avail. As of April 12, the government had yet to ask the United States for assistance in getting China to release more information about Lee’s detention or to free him.

Lee’s detention, and the lack of information surrounding his situation, will only worsen China-Taiwan relations, which have been aggravated by a series of security-related incidents over the past two years. China has increased surveillance missions around Taiwan since late 2016, and sailed its aircraft carrier through Taiwan’s air defense identification zone in the Taiwan Strait in January. Taiwan has recently made a number of naval and aviation upgrades, even announcing that its missiles could strike the mainland. And then there’s the controversy surrounding the (in)famous phone call between President Trump and Tsai in December.

One reason why China hasn’t responded formally when contacted by Taiwan is that China suspended official communication mechanisms with Taiwan in May because China felt that Tsai did not adequately show her support and acceptance of the 1992 Consensus, a key understanding between the two sides regarding the one-China principle, during her inaugural address. And most recently, in March, Taiwan detained a man from China on suspicion of organizing a spy ring and breaching national security laws. Lee’s detention could be reprisal for the detention of Zhou Hongxu, the suspected spy.

The U.S. government’s silence on the matter hasn’t helped. A group of Taiwanese activists held a news conference before the scheduled Trump-Xi summit because Joshua Wong, an activist from Hong Kong who participated in the briefing, and others feared “that human rights might be pushed aside in the trade-focused talks.”

Those fears were warranted because Taiwan barely figured in the two-day summit’s agenda. Secretary of State Rex Tillerson specifically mentioned that human rights were not a topic of discussion during his briefing. He claimed that human rights are “embedded in every discussion,” but this merely serves as a sign to China that human rights are not a critical part of the Trump administration’s agenda. Sometimes, what’s not on the agenda is just as important as what is on it. The message to China was quite clear.

By contrast, hundreds of human rights groups in Taiwan and around the world have been very vocal. The Taiwan Association for Human Rights spearheaded a signature drive. Amnesty International, Freedom House and Human Rights Watch, among many others, have spoken out against China’s behavior and Lee’s detention.

China has the power to do whatever it wants (including keep silent), but this situation will only worsen its human rights reputation globally. Human rights must be an explicit agenda item when democratic leaders meet with authoritarian leaders, and it is incumbent upon democratic nations to pressure authoritarian countries to uphold the sanctity of human rights. Otherwise the autocrats will have a free hand at shutting down legitimate activism and imprisoning activists without complaint. Lee’s detention in China is just one example of what is to come if the Trump administration does not change how it thinks about human rights discussions.