North Korea closed its land border with China for trade and visitors and summoned back state workers living on the Chinese side to prepare for the funeral of late leader Kim Jong Il, according to Chinese officials and people in contact with North Koreans.

The blocking of the country's main economic lifeline appears to be a temporary move to allow the government to focus on the funeral on Dec. 28, but it also affords Mr. Kim's son and successor, Kim Jong Eun, a chance to enforce absolute control over his country's borders and citizens.

Some Chinese businesspeople who work with North Korea said on Tuesday that they thought the younger Mr. Kim could bring reforms. But dissidents in Seoul told reporters on Tuesday that the pace of change could be slow, and that the Pyongyang regime is stronger than outsiders presume.

Rim Chun-ryong, who served in the North Korean army for 17 years before he fled the country in 2000, said that breaking the mindset in North Korea is hard because people there are so deeply immersed in propaganda and showing dissent is unthinkable.

"Even if you aren't sad and don't want to cry, you should cry," he said. "If tears don't come out, you should at least wet your face with spit. That's North Korea. It's much more solid than you think," he said in an interview.