Russia's Gazprom and a group of European companies agreed on the project last year, raising protests mostly among central and southern European countries.

“The advent of [more sellers of] LNG is another challenge of the gas market,” Adeli said and noted that the U.S. has utilised modern technologies to produce gas from shale, so that the country has been turned from a gas importer to an exporter. Australia, another OECD country with no interest in joining organisations that could be seen as cartels, is already an LNG exporter and its output is rising sharply over the coming few years.

“Given the volumes of gas shipped to Europe, the marginal cost of additional Russian gas is low and they should be able to compete with US LNG supplies,” said Malcolm Johnson, a Guildford, England-based faculty member of The Oxford Princeton Programme, an energy training provider. “However, it is clear that in certain countries there is a desire to diversify supplies for supply security.”

Mr. Novak said that the project could still be implemented if the European Commission develops corresponding infrastructure for natural gas transportation in Central and Eastern Europe,

Gazprom’s “export policy has always been balanced and adaptive,” says spokesman Sergei Kupriyanov. He argues that European customers have become more interested, not less, in Russian gas, given Europe’s own decline in production.

I think Russia would be happy if the Southern Corridor did not happen, but I think at this point it's a fait accompli – it will happen. The Shah Deniz project has been approved and a final investment decision has been taken. Work is progressing on it and on the Trans Anatolian Pipeline (TANAP) that will cross Turkey and go on into Europe. The present issues between Turkey and Russia will only strengthen the resolve for completing the Southern Corridor. The question will be how much the Southern Corridor can expand beyond the currently planned quantities of 10 bcm to Europe and the 6 bcm to Turkey. It is also a question of whether there will be other gas sources that can put gas into that pipeline system.

In 2015, Gazprom increased market share in Europe and Turkey by one percentage point, from 30.2% to 31.2%,

Russian Economy Minister Alexei Ulyukayev put it more bluntly, telling reporters in Brussels that blocking Nord Stream-2 would be "a shot in the foot" especially for Gazprom's European clients.

Gazprom and some utilities say Nord Stream-2 is the most pragmatic solution to shoring up Europe's energy security. The European Commission has said it is assessing its legality.

Donald Tusk, president of the European Council, became the latest senior politician to criticise plans for a new pipeline bringing Russian gas to Germany, saying it would undermine the EU’s goal of reducing energy dependence on Moscow.