Though President Bush returned to Washington Thursday afternoon after a two-day jaunt pitching initiatives he outlined in his State of the Union address to the heartland, the chief executive was not softening his call for increased homeland security.

Bush said in his address Tuesday night that he wanted to use the Sept. 11 attacks to change the culture of America, including increasing the amount of volunteering people do. For the next few weeks, the president is expected to paint a picture of a country under siege.

In Atlanta on Thursday, Bush reiterated that Al Qaeda trained thousands of "ticking time bombs" and, although he did not mention them by name, repeated his warning to North Korea, Iran and Iraq, nations he said form an "axis of evil."

"One thing they've got to know for certain is we will not let them use their weapons of mass destruction to threaten the security of the United States of America," the president said. "They are on notice and I expect them to make the right decisions about being a peaceful nation. ... A nation that respects common values and a nation that adheres to freedom."

He reassured the crowd that he would do everything possible to prevent future attacks.

"Even though the enemy thinks they're going to hit us again, you need to know your federal government is doing everything we can to stop them. We are on full alert," Bush said.

Earlier in the day, the president witnessed examples of the kind of public service he wants to see more of. Daytona Beach volunteer firefighters showed him how they respond to emergencies, and the president spoke to local Senior Corps members, emphasizing the contributions senior citizens can volunteer to their communities.

"There are numerous seniors who've got a lot to offer," Bush said. "People might be retired, but their brains haven't retired and their experience hasn't been retired."

Bush also discussed a program called "Citizens on Patrol," in which more than 200 volunteers put in 51,000 hours in the year 2001 helping local law enforcement.

The president also promoted USA Freedom Corps, which he set up by executive order Wednesday, consolidating the three volunteer-service agencies AmeriCorps, Senior Corps and the Peace Corps into one.

Bush aims to expand AmeriCorps and Senior Corps, both started by former President Clinton, by 100,000 volunteers. He also wants to widen the 40-year-old Peace Corps' activities in Muslim countries.

The president has asked for each American to contribute 4,000 hours throughout his life. He told assembled members of the Senior Corps that they could access USAFreedomCorps.gov, a government Web site, to learn more about ways they can help.

Administration officials say they think volunteerism could triple if the president makes a good case for it. Bush plans to encourage retired medical professionals and other specialists to enlist in a "Citizens Corps." He also plans to warn Americans that the terrorist threat is still very real.

John Bridgeland, former director of the president's Domestic Policy Council, will take over as executive director of Freedom Corps.

Bush acknowledged Wednesday that his urging seemed more like a television advertisement than a presidential appeal.

"It sounds like I am making a pitch, and I am; this is the right thing to do for America," Bush said.

According to a CNN/Gallup poll conducted after the State of the Union address, 80 percent of Americans said they would be willing to commit two years over their lifespan to community service.

Fox News' Wendell Goler contributed to this report.