President Bush waves to the crowd after a speech on homeland security and the war on terrorism at Chrysler Hall in Norfolk, Virginia

President Bush has called the ideology of Islamic radicals the great challenge of the 21st century.

The president spoke Friday in Norfolk, Virginia, home to the world's largest naval base, to a receptive audience that often broke into applause.

The president compared Islamic radicals to dictators from the past including Hitler and Stalin. He said such militants must be taken seriously and stopped before their crimes multiply. He said protecting the freedoms of others in the world protects freedom in the United States.

Mr. Bush stressed that Islamic radicalism is very different from Islam.

During his speech, a protester in the audience yelled, "Mr. President, war is terror," and revealed a shirt saying "Dump Bush." He was escorted out of the auditorium, as other audience members voiced their disapproval of him.