Protesters wear masks of Chinese Nobel Peace Prize laureate Liu Xiaobo. (Bobby Yip/Reuters)

FOR TWO decades, Liu Xiaobo has been one of China’s foremost advocates of human rights and peaceful democratic reform. For that, he was awarded the Nobel Peace Prize in 2010 — but he has also suffered unrelenting persecution and mistreatment by his own government. Now comes the ultimate abuse: Having failed to treat Mr. Liu for liver cancer until it was too late to do so, the regime of Xi Jinping has transferred him to a hospital in the city of Shenyang — so that it cannot be said that he died in prison. This cosmetic act of clemency should not stop the democratic world, led by the United States, from holding China up for condemnation for its unconscionable treatment of one of its most important freedom fighters.

Mr. Liu was a leader during the 1989 pro-democracy demonstrations in Beijing’s Tiananmen Square. But his most important contribution was his work in authoring Charter 08, a petition calling for freedom of association, an independent legal system, separation of powers and other elements of liberal governance that would allow China to “join the mainstream of civilized nations.” Mr. Liu was the first of more than 10,000 people who signed; for that he was arrested and, in 2009, sentenced to 11 years in prison. His wife, Liu Xia, was illegally placed under house arrest; anyone else who supported him was subjected to persecution.

When the Nobel Committee chose Mr. Liu, China became the first regime since Nazi Germany to prevent an honoree or their family members from traveling to Oslo. Since then, it has worked relentlessly to silence support for him abroad as well as at home, with lamentable success. President Barack Obama spoke out only once on behalf of Mr. Liu, and many other Western leaders were altogether silent — perhaps intimidated by the punishments the regime inflicted on Norway after the Nobel was awarded. Since taking power in 2012, Mr. Xi has greatly increased repression of liberal voices, including not just democracy advocates but also liberal academics, journalists and lawyers who defend those subjected to abuses of power. He seems intent on establishing that China will never embrace the freedoms that Mr. Liu fought for.

On Tuesday , the State Department joined human rights activists in calling on China to allow Mr. Liu freedom to travel to a place of his own choosing for medical care. According to a U.S.-based advocate, Jared Genser, the 61-year-old dissident has asked authorities to allow him and his wife to travel to the United States. But the U.S. statement came from a low-level official, the spokeswoman of the embassy in Beijing, when it ought to be delivered directly by President Trump to Mr. Xi. Mr. Liu’s case is a signal example of why China lacks the moral capacity to exercise global leadership. By advocating for this dying hero of human rights, Mr. Trump could show that the United States still lives by different values.