Heavy rains lashing China's north-east and Russia's far east have not only unleashed massive floods but also looked to have stirred up bad blood, as the neighbours accuse each other of channelling unwanted water across the border.
The worst flooding seen in years has affected 3.7 million people and caused at least 72 deaths in China's north-east and prompted the evacuation of up to 100,000 in the Russian region.
Torrential rain in the past few weeks has burst the banks of the Amur River, which is called Heilongjiang in Chinese. The river runs through both countries and forms the border between the Chinese province of the same name and Russia's Amur, Khabarovsk and Jewish autonomous areas.
State broadcaster China Central TV (CCTV) said Russia's release of floodwater into the Amur has exacerbated the situation downstream in China. The water level of Heilongjiang near Jiayin county has risen by 30cm daily since Aug 7, CCTV reported last Saturday.
Some Chinese netizens have also hit out at Russia. "Treating our Heilongjiang province as a reservoir for flood water. What a great ally!" wrote a netizen nicknamed The Happy Life Of A Ghost on Sina microblog, referring to Russia.
Said Madam Ma Airong, 50, a hostel owner from Heilongjiang's Mohe county bordering Russia: "When they release water from their reservoir, we are affected."
Four years ago, she told The Straits Times, she and other villagers were forced to flee to higher ground to escape the rising water.
Russian officials, in turn, have pointed the finger at China.