Secretary of State Condoleezza Rice gently prodded South Korea on Wednesday to show a strong commitment to international sanctions imposed against North Korea for its nuclear test this month.

Rice said the U.S. has no wish to tell Seoul how it should coexist with its neighbor and noted the vigorous debate in South Korea over the future of its "sunshine policy" of partial rapprochement.

But she said North Korea's test of a nuclear device Oct. 9 "requires a strong response," and said that adherence to a U.N. resolution banning the sale of weapons material, luxury goods and more to North Korea is key. The sanctions also seek interception of ships believed to be carrying suspect materials.

"It requires a strong commitment by South Korea," she told the conservative Heritage Foundation. "Any activities need to be seen in the light of making certain to implement that resolution."

South Korea so far has balked at taking strong measures to support the sanctions, mindful of Pyongyang's massive armed forces poised at the border, its family and cultural ties with the North and its wish to expand economic relations with its neighbor.

"We understand that this is a complicated set of issues for South Korea," she said. "South Koreans don't need us to tell them what to do about their policies."

Rice returned Sunday from a weeklong trip to Asia and Moscow to line up support for the U.N. resolution, approved five days after the North's nuclear test.

"North Korea's behavior poses a regional challenge and it must be addressed in a regional context," she said. "South Korea must be part of the solution, as should Japan and China and Russia.

"These countries all share an interest in a denuclearized Korean Peninsula. They all have leverage to help bring it about. And they must all accept their share of the responsibility to help," Rice said.