The organization’s high commissioner for human rights, Zeid Ra’ad al-Hussein, implicitly criticized China in a condolence statement by describing Mr. Liu as a champion who had been “jailed for standing up for his beliefs.”

But António Guterres, the secretary-general, was more circumspect. Asked for a comment, his spokesman, Stéphane Dujarric, said Mr. Guterres was “deeply saddened,” but he did not address the circumstances of Mr. Liu’s death or the restrictions on Mr. Liu’s wife. “I don’t have anything further to say at this point,” Mr. Dujarric told reporters on Thursday.

In 1989, Mr. Liu was detained for nearly two years after the Chinese government called him a “black hand” who supported the student demonstrators who crowded Tiananmen Square before an armed crackdown. Back then, Communist Party leaders railed against Western-inspired subversion and imprisoned leading participants in the protests who hadn’t fled.

Yet China was more vulnerable to pressure, and sometimes made concessions.

It was the world’s ninth-biggest economy in 1989, and needed expertise, investment and technology from advanced countries to begin growing again. It did not have a wide circle of countries that would help it thwart Western sanctions and isolation. And the party general secretary and later president, Jiang Zemin, appeared eager for affirmation and even friendship from President Bill Clinton and other Western leaders.

But since China joined the World Trade Organization in 2001 and its economy took off, leaders in Beijing have become increasingly set against making concessions on human rights cases. That posture has reflected China’s economic and diplomatic strength. But it has also reflected leaders’ longstanding fears that, even with robust growth, broad public support and a powerful police apparatus, they are vulnerable to political foes.

From 1989 to 2008, when Mr. Liu helped start Charter 08, a petition for democratic change, he and other dissenters still hoped that the Communist Party could be coaxed to give citizens greater freedoms, pushed by civic mobilization in China and encouraged by Western governments and groups. Even if there were occasional setbacks, many believed expanding market forces and a growing middle class would shape history in their direction and would make the government ultimately accept political liberalization.

“China’s economy is growing quickly, and this economic development is supportive of a political transformation,” Mr. Liu said in an interview in 2004. “China’s international environment has seen big changes, and there’d be very strong international support for its political reforms.”