WASHINGTON — President Bush, honoring the memories of those killed in communist regimes, said yesterday that their deaths should remind the American public that “evil is real and must be confronted.”

In dedicating a memorial to those victims, Mr. Bush linked periods of totalitarian rule to the September 11, 2001 attacks.

“Like the communists, the terrorists and radicals who attacked our nation are followers of a murderous ideology that despises freedom, crushes all dissent, has expansionist ambitions, and pursues totalitarian aims,” Mr. Bush said. “Like the communists, our new enemies believe the innocent can be murdered to serve a radical vision.”

Tens of millions of people were killed in communist regimes, from China to the Soviet Union, Cambodia to Africa, North Korea to Vietnam.

Mr. Bush spoke on the 20th anniversary of one of President Reagan’s most famous moments — a speech at the Berlin Wall in which he challenged Soviet leader Mikhail Gorbachev to “Tear down this wall.” It was the ultimate challenge of the Cold War, and the wall fell in 1989 as communist rule collapsed in East Germany and Soviet-dominated Eastern Europe.

In turn, Mr. Bush said it was time to recall the lessons of the Cold War: “that freedom is precious and cannot be taken for granted; that evil is real and must be confronted; and that given the chance, men commanded by harsh and hateful ideologies will commit unspeakable crimes and take the lives of millions.”

The Victims of Communism Memorial, within view of the Capitol, was more than a decade in the making. It aims to honor memories and educate current and future generations about communism’s crimes against humanity.

At its center is a woman holding what Mr. Bush called a “lamp of liberty.”

“She reminds us that when an ideology kills tens of millions of people, and still ends up being vanquished, it is contending with a power greater than death,” Mr. Bush told roughly 1,000 invited guests. Mr. Bush’s comments came the day after he returned from a six-country swing through Europe.