Secretary of State Condoleezza Rice arrived in Seoul Saturday, a day after neighboring North Korea destroyed the cooling tower at its main nuclear facility.

Rice said that even after North Korea handed over inventory of its nuclear activities, mostly outlining Pyongyang's program to produce arms-grade plutonium, the country still had not answered to allegations of uranium enrichment and nuclear proliferation.

"Thus far we don't have the answers we need on either," Rice said at a news conference.

The demolition followed U.S. moves earlier this week to lift sanctions against the communist country in response to its submission of a long-delayed declaration of its nuclear programs.

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"I expect that the North will live up to the obligations that it's undertaken, to take those concerns seriously and to address them," Rice said of information left out of the declaration. "At the end of this, we have to have the abandonment of all programs, weapons and materials."

Rice later met with South Korean President Lee. She briefed Lee on recent progress in the nuclear standoff, and Lee told her that their two countries should work closely together to get North Korea to give up all nuclear weapons and programs, the presidential Blue House said.

Rice also insisted Saturday that American beef is safe to eat and urged South Koreans to accept their government's decision to lift a ban on the meat.

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Rice said she hoped the beef controversy won't distract from important issues facing the United States and South Korea, most notably the six-nation talks over North Korea's nuclear program.

"In terms of differences that sometimes arise from trade disputes, they are normal in relations between states," Rice told a joint news conference with South Korean Foreign Minister Yu Myung-hwan.

In South Korea, the long-running nuclear issue has been of less public concern than Seoul's agreement to lift a ban on American beef imports in April as a way to restore strained ties with Washington.

Activists have been staging daily rallies on the streets of Seoul to voice their concerns about possible health risks such as mad cow disease. As officials began inspecting U.S. beef Friday before it can reach markets, hundreds of labor activists blocked customs storage facilities.

"I can only say that American beef is safe and we hope that in time the South Korean people will listen to that and will be willing to listen to what their government is saying and what we're saying," Rice said earlier en route to Seoul. "The U.S. believes strongly in the safety of its product."

U.S. beef had been banned from South Korea for most of the past 4 1/2 years, since the first case of mad cow disease in the U.S. was discovered in late 2003. In the wake of public outrage over plans to resume shipments of American beef, the entire South Korean Cabinet has offered to resign and President Lee Myung-bak has reshuffled his top advisers.

Seoul agreed to resume U.S. beef imports after American producers agreed to limit shipments to meat from cattle younger than 30 months, believed less susceptible to mad cow disease. The restriction has been deemed a transitional step that will be lifted when conditions change in South Korea.

"It will take time for that risk to be erased from the minds of the Korean public," Foreign Minister Yu said.

A loud and angry group of about 15 sign-carrying protesters gathered outside the South Korean Foreign Ministry where Rice was meeting with government officials.

"Stop Rice and Mad Cows," said one placard. "We Don't Need U.S. Troops. We Don't Need Mad Cows," read another.

A squad of black-clad police surrounded the anti-U.S. demonstration, which was minuscule compared to earlier rallies that drew up to 80,000 people but have since dwindled.