Energy specialists see China's new deal to import natural gas from Russia as a costly but necessary step toward energy diversification.

On Wednesday, President Xi Jinping and his Russian counterpart Vladimir Putin oversaw the conclusion of the decade-long negotiations over Russia's gas supply to China.

Under the roughly $400 billion pact, Gazprom will supply China with 38 billion cubic meters of gas annually for 30 years, starting in 2018, through the planned "eastern pipeline", which will connect Russia to China's northeastern Heilongjiang province, and from there connect with the industrialized cities along China's eastern coast.