Japanese experts welcomed Wednesday's developments between Japan and North Korea in Shenyang, China, as critically important, but also warned that Japan should not be in a rush to lift sanctions.

"North Korea pledged to deliver results in its reinvestigation of its abduction of Japanese nationals by this fall, which is a very short time span. This reflects their strong determination to make progress on the issue," said Masao Okonogi, professor at Keio University and an expert on North and South Korean politics.

Okonogi said Pyongyang's speed may have been influenced by its negotiations with the United States, as North Korea's compromise came only two days after Washington chose not to remove the North from its list of terrorism-sponsoring countries.