He said that free societies emerge "at different speeds in different places," but that certain values are universal to all democracies.
Bush's speech was a plea for what he called "the freedom agenda." (Read the complete text of Bush's speech.)
His audience included dissidents and democratic activists from around the world. And there were some notable absences, he said.
"In Russia, reforms that were once promised to empower citizens have been derailed, with troubling implications for democratic development." -- President Bush
"There are many other dissidents who couldn't join us because they are being unjustly imprisoned or held under house arrest," Bush said. "I look forward to the day when conferences like this one include Alyaksandr Kazulin of Belarus, Aung San Suu Kyi of Burma, Oscar Elias Biscet of Cuba, Father Nguyen Van Ly of Vietnam, Ayman Nur of Egypt."
Freedom Under Assault
Bush evoked the history of his host city, Prague, saying communist rulers had proven no match for the resolve of dissidents like Vaclav Havel.
"Freedom can be resisted, and freedom can be delayed -- but freedom cannot be denied," Bush said.
He said freedom was under assault around the world, even where there had been some progress. From Vietnam to Uzbekistan, rights or political activists were in jail. He called those developments discouraging, but said there were more reasons for optimism.
"The United States has nearly doubled funding for democracy projects," he said. "We are working with our partners in the G8 to promote the rise of a vibrant civil society in the Middle East through initiatives like the Forum for the Future. We are cooperating side-by-side with the new democracies in Ukraine, Georgia, and Kyrgyzstan."
Then there are countries Bush said were being urged to move toward democracy, "valued partners" like Egypt, Saudi Arabia, and Pakistan.
The United States can maintain friendship with such countries, Bush said, and push them toward democracy at the same time.
The Russia Problem
And then there's Russia.
Relations between Russia and the United States have become increasingly strained by U.S. plans to build a missile shield in the Czech Republic and Poland, and Russian President Vladimir Putin has warned Moscow could respond by aiming Russian missiles at European targets.
Earlier today, Bush discussed the plans with Czech leaders, and said Russia was "not the enemy" of the United States and had nothing to fear from the plan.
In his speech, Bush said the United States had a complex relationship with Moscow, with mutual interests but also strong disagreements.
"In Russia, reforms that were once promised to empower citizens have been derailed, with troubling implications for democratic development," Bush said. "Part of a good relationship is the ability to talk openly about our disagreements. So, the United States will continue to build our relationships with these countries [Russia and China], and we will do it without abandoning our principles or our values."
Bush will have a chance to talk directly to Putin about the missile-defense plans and other sources of disagreements soon.
The two are due to meet on the sidelines of a summit of the Group of Eight major industrial nations in Germany on June 6-8.
AN RFE/RL VIDEO PRESENTATION: The Czech Republic responds to the U.S. missile-defense proposal.