On one side of the border, Russian gas workers, clad in gray and blue, stood at attention in the Atamanskaya gas compressor station near Blagoveshchensk, close to the Chinese border, waiting for Putin's order to start the flow.
"China's apparent consumption (total of a country's gas production plus imports minus exports) of natural gas will reach about 310 billion cubic meters in 2019, up about 10 percent over last year", a Chinese government report said earlier this year.
The pipeline will diversify Russia's gas market while providing China with an alternative steady gas supplier, said Alexei Belogorey, deputy executive director on energy studies at Russia's Institute for Energy and Finance Foundation.
President Vladimir Putin, Deputy Prime Minister Dmitry Kozak, Energy Minister Alexander Novak and Chief Executive of Gazprom Alexei Miller take part in a ceremony launching the Power of Siberia gas pipeline to China via a video link in Sochi, Russia, on December 2, 2019.More news: Trump says China trade deal might have to wait for 2020 election
The two countries can jointly tap potential markets and "Russian companies could also build gas transmission grids and underground gas storage in China with their unique expertise in the field", Belogorey said.
The natural gas supply from Russian Federation is expected to change that, starting with the city of Heihe, which has already seen more than 30,000 people switching from coal to natural gas, according to Xinhua.
Xi called it "a landmark project of China-Russia energy cooperation and a paradigm of deep convergence of both countries' interests and win-win cooperation". It will transport 38 billion cubic meters per year (Bcm/y) of Russian gas to China, under a 30-year supply deal with CNPC.
The pipeline comes after years of tough negotiations and work in hard conditions, considering that the Power of Siberia pipeline runs through frigid, swampy, mountainous, and seismically active regions of Russian Federation.
Xi said the project "serves as a model of... mutually beneficial cooperation between our countries".More news: NASA Will Attach A 'Robot Hotel' To The International Space Station
In a symbol of the strengthening military ties between Moscow and Beijing, Russia and China staged their first joint air patrol in the Asia-Pacific in July, scrambling Japanese and South Korea air defenses.
Gazprom chief Alexey Miller said 10,000 workers took part in the construction of the pipeline, which used 130,000 pipes.
Construction began in June 2015, and the pipeline is expected to be completed in 2020. But the project could be frustrated if threatened US sanctions against companies laying the pipeline are imposed.
The over 4,000 km gas pipeline has an annual capacity of over 61 billion cubic metres and passes through wetlands, mountainous terrains, seismically active zones, areas of permafrost and rocky ground.More news: Jay-Z Puts Entire Catalog Back on Spotify for 50th Birthday