Seoul, South Korea ? Secretary of State Condoleezza Rice said Thursday she would not try to dictate how U.S. allies enforce sanctions on North Korea for its nuclear program, and there were signs South Korea wouldn’t quickly embrace Washington’s approach.

“The key is to live up to the obligation that all of us undertook” to bar North Korea from exporting nuclear technology or receiving overseas help for its nuclear program, Rice said after meetings with South Korea’s president and top diplomat.

South Korea and China are the communist North’s closest neighbors and trading partners, accounting for two-thirds of its foreign commerce.

Both nations are pledged to carry out U.N. restrictions approved after North Korea’s Oct. 9 test explosion of a small nuclear device, but they have hedged on details. Rice visits Chinese leaders today in Beijing.

In China, officials with four commercial banks said they have stopped moving funds in and out of North Korea, The Wall Street Journal Asia reported Thursday on its Web site, and one of the officials cited a ban ordered by Chinese regulators.

A senior U.S. official confirmed that the Chinese were taking “unusual measures” against the North Koreans in their banking system but would not elaborate. The official spoke on condition of anonymity because Rice had not yet discussed the issue with her Chinese counterparts.

South Korean protesters are blocked by riot police officers Thursday during a visit by U.S. Secretary of State Condoleezza Rice to the U.S. Embassy in Seoul. Rice said Thursday that she wouldn't try to dictate how U.S. allies enforce sanctions on North Korea.

Rice is on a crisis mission to Asia to reinforce the sanctions and reassure jittery allies of U.S. support. But she played down differences on how to confront Pyongyang, and left U.S. expectations vague.

“I did not come to South Korea nor will I go anyplace else to try to dictate to governments what they ought to do” to enforce the U.N. mandate, Rice said at a news conference with South Korean Foreign Minister Ban Ki-moon.

Ban said Seoul will review the terms of economic projects it has undertaken with the North “in harmony and in line with the U.N. Security Council resolution and international demands,” but he made no promises.

The United States is skeptical about a pair of landmark inter-Korean projects – a tourism venture and joint economic zone in North Korea – that are symbols of hope for the peninsula’s reunification. U.S. officials have suggested the tourism project in particular serves to funnel badly needed hard currency to the North Korean regime.

A senior State Department official traveling with Rice said Seoul is likely to announce changes to the projects or other means of meeting the sanctions requirement after Rice has left the region, so as not to appear to have caved to U.S. demands. The official spoke on condition of anonymity because Rice’s consultations were private.

South Korea has said it would fully comply with the sanctions but also has indicated it does not plan to halt key economic projects with the North.