^probably old
More details on the river access and map of the location
Russia may sell out a river access to China
"BEIJING -- China, Russia and North Korea are expected to start discussions soon about allowing ships to navigate a border river into the Sea of Japan, which could have major security implications for Tokyo.
The waterway, the Tumen River, flows east along the border of China and North Korea, and eventually also of Russia, before emptying into the Sea of Japan.
Chinese vessels can currently only freely navigate the river until the village of Fangchuan, on the eastern end of landlocked Jilin province. Permission is required from both Russia and North Korea to navigate the remaining 15-kilometer stretch to the Sea of Japan. A Soviet-era, 7-meter-tall bridge also blocks the passage of larger vessels.
(...)
China historically held the area until the Russian Empire took control in the 1860s. China has repeatedly urged Russia and North Korea to allow Chinese vessels to navigate the river to the Sea of Japan, proposing the creation of a special economic zone along its banks.
Russia used to be reluctant on the idea, concerned that it would increase China's influence in Northeast Asia. But its attitude is changing as the power dynamic between Moscow, Beijing and Pyongyang shifts.