North Korea watchers were reduced to feverish speculation as the customary news blackout blanketed a visit from a high-ranking Chinese apparatchik to Pyongyang.
Li Jianguo, a vice chairman of National People's Congress of China, arrived in the North on Thursday.
In an attempt to gauge how close the two allies really are, South Korean officials focused on whether young North Korean leader Kim Jong-un will be invited to China.
One official here said there is "a chance" that Li will invite Kim to China on behalf of new Chinese leader Xi Jinping.
It is not known whether Li will meet Kim, but if he does he will be the first senior Chinese official to do so since Xi took helm.
The visit comes amid signs that North Korea is preparing to launch a space rocket, which is widely seen as a cover for testing long-range missile technology.
Originally China said it was sending Liu Qibao, the head of the Publicity Department of the Chinese Communist Party, but it instead dispatched Li, a higher-level official.