A bust of Vaclav Havel, the first president of the Czech Republic in on display following an unveiling and dedication ceremony in National Statuary Hall on Capitol Hill in Washington, Wednesday, Nov. 19, 2014. (Susan Walsh/AP)

THE 25TH anniversary of the anti-Communist revolution in Central and Eastern Europe has been marked by celebrations but also by worrying signs that some of its signal achievements are threatened. Since 1989, six former members of the Soviet-dominated Warsaw Pact (or their successor states) have transformed their economies, joined the European Union and NATO, and established democracies. Their achievements look particularly impressive when set alongside the chaos and civil wars that have followed the Arab uprisings of 2011.

Nevertheless, in much of Central and Eastern Europe, the ideals of leaders such as dissident-turned-Czech president Václav Havel, who this week was honored with the unveiling of a bust at the U.S. Capitol, are under assault. The current Czech government has distanced itself from Mr. Havel’s human rights agenda and is dismantling a program he created to support democratic transitions in other dictatorships. President Milos Zeman has become a virtual mouthpiece for Russian President Vladi­mir Putin, denouncing Russian political prisoners in vulgar terms and denying Russian aggression in Ukraine. Even more troubling is Hungarian Prime Minister Viktor Orban, who has dismantled democratic checks and balances in Budapest while citing Mr. Putin as a model.

It therefore has been heartening that this week — the anniversary of the Velvet Revolution Mr. Havel helped to lead against the Communist regime in then-Czechoslovakia — has seen an eruption of pro-democracy and pro-Western sentiment around the region. In Prague and Budapest there were large demonstrations Monday against Mr. Zeman and Mr. Orban. The former was the target of hurled eggs when he appeared at an event to commemorate the revolution, as protesters chanted, “We don’t want to be a Russian colony.” In Budapest, site of the fourth large anti-government demonstration in a month, the crowd demanded the dismissal of corrupt officials, including several who have been banned from entering the United States.

Even more encouraging was Sunday’s presidential election in Romania, where populist leftist Prime Minister Victor Ponta was upset by a small-town mayor who promised to root out corruption and improve relations with the West. Klaus Iohannis, a member of Romania’s small German minority inspired a big turnout — 64 percent — by promising to back prosecutions of senior officials for corruption and to strengthen Romania’s strategic partnership with the United States and NATO. Though he sometimes sounded pro-Western notes, Mr. Ponta also challenged democratic norms, prompting concerns that he would follow the course of Mr. Orban.

Mr. Orban and Mr. Zeman still have substantial support in their countries. But it is heartening that many of those turning out against them are students and other young people who did not experience the 1989 revolution or the previous Communist era — and yet who embrace Western liberal values, and not Putin-esque nationalism, with its ugly overtones of hatred for homosexuals and other minorities.

For his part, Czech Prime Minister Bohuslav Sobotka, a party rival of Mr. Zeman, traveled to Washington for the unveiling of the Havel bust and praised Havel’s principled foreign policy. The contest in former Communist Europe between pro-Western liberals and their populist, nationalist or authoritarian opponents is far from over — but this anniversary week was a good one for Havel’s followers.