There has been closer cooperation between these two powers in recent years, but Russia is still concerned about Chinese ambitions. From Pravda:
China is trying to change its borders with Russia again. Spokesmen for the Border Service Agency of the Federal Security Bureau said that, on April 13 and 14 Chinese vessels and barges with excavators aboard were conducting dredging operations in the area of the 146th kilometer of the Ussuri River. The same works were conducted on April 17, in the area of the 215thkilometer of the Ussuri River, in the Khabarovsk region, Russia.
The Chinese vessels unloaded the excavated soil on other parts of the river, which may also change the watercourse of the border river, Russian official said.
The above-mentioned activities were conducted without Russia’s agreement, which violated the inter-governmental border agreement between the two countries.
Such reports arrive from the Far East of Russia on a regular basis, almost every year. Every time when it happens, Russia asks for explanations, but China leaves Russian inquiries ignored.
Moscow handed over the islands on the Amur River near the city of Khabarovsk under China’s control in an attempt to solve the territorial dispute with the Celestial Empire once and for all. China has not set any territorial claims to Russia yet, but it just so happens that the country is trying to do it in an artful way.”
You can read the full report here.