U.S. Assistant Secretary of State Kurt Campbell says movements observed around the border area between North Korea and China may be related to preparations for a visit to China by North Korean leader Kim Jong-il.

According to Japan’s Yomiuri Shimbun, Campbell told reporters at an airport near Washington that there are signs Kim may soon visit China, but that no other details have been confirmed.

The Japanese newspaper said the U.S. may have detected signs pointing toward a visit to China by the North Korean leader through its reconnaissance satellites.