North Korea has started building a fence along parts of its border with China, a news report said Sunday, in an apparent move to prevent North Koreans from fleeing the impoverished communist country. The North has put in place posts along a 10-kilometer (6 mile) stretch along a narrow tributary of the Yalu River, which marks the border between North Korea and China, and has also built a road to guard the area, Yonhap news agency reported. The North has yet to string barbed wire fencing between the posts, Yonhap reported. The fence comes less than a year after China built a massive barbed wire and concrete fence along its side of the same river. North Korea and China share an 880-mile (1,416-kilometers) border.