U.S. Secretary of State Condoleezza Rice (search) on Sunday extolled the virtues of free and open societies at a news conference in the South Korean capital, after security guards wrestled a man to ground as he loudly called for American intervention to free communist North Korea.

"Miss Rice, the North Korean people are dying and they are crying for your help," yelled the activist, German physician and former aid worker Norbert Vollertsen (search). He held up a poster that read, "Freedom for North Korea: 50 Years Overdue," until an embassy employee ripped it in half.

As Rice took her seat for the conference, security officers were literally muffling Vollertsen as they wrestled him to the floor. He had talked his way into the media gathering before Rice arrived, but an embassy public affairs officer recognized him at the last moment and demanded he be removed.

It was a rocky start to an unusual news conference with Korean Internet reporters, meant to highlight the medium's freewheeling nature in an open democracy. Rice was also expected to meet with South Korean (search) officials Sunday to discuss the communist North's nuclear ambitions.

In replies to the Korean journalists, Rice described true democracy as the ability to "say what you wish, worship as you please and educate your children, boys and girls."

In contrast to the closed society of North Korea, Rice said, "you can come here and think what you want and ask me anything -- the United States secretary of state -- and what a wonderful thing that is."

On Saturday, Rice became the most senior American official to tour a command center for U.S. and South Korean troops that would be the battle headquarters in the event of fighting with the communist North.

"I know that you face a close-in threat every day," Rice told troops at Command Post Tango, or Theater Air Naval Ground Operations, late Saturday.

Rice's visit coincided with a twice-yearly war exercise involving thousands of American and South Korean soldiers. When Rice got a look at the command center, it also was the first time that reporters and cameras were allowed into the bunker south of Seoul.

North Korea denounced the exercises as a rehearsal for a U.S.-led pre-emptive attack.

"The Republic of Korea, a great democracy now, faces a threat across the divide of a state that is not democratic, that is not free, and that does not have the best interests of its people at heart," Rice said, referring to South Korea by its official name.

Rice appealed to North Korea's closest ally, China -- which she was scheduled to visit Monday -- to use its leverage to bring the North back to disarmament talks.

The United States, Russia, Japan, South Korea and China began a joint diplomatic effort with North Korea last year aimed at persuading the country to give up its nuclear program.

But the six-nation talks, hosted by China, stalled in September, when the North Koreans pulled out and refused to return to the discussions. North Korea announced last month it has built a nuclear weapon.

The North Koreans have not responded to a U.S.-backed peacemaking proposal and have demanded an apology after Rice this year branded the country an "outpost of tyranny."

North Korea has said it wants nuclear weapons as a defense against a potential attack from U.S. and South Korean forces.