July 11 (UPI) -- Russia shut down Europe's largest gas pipeline, Nord Stream 1, for annual maintenance on Monday, but some are concerned that the 10-day closure could be extended for "political reasons" as the continent scrambles to store energy supplies for the winter.
Nord Stream 1, which carries about 55 billion cubic meters of fuel every year under the Baltic Sea from Russia to Germany, will remain shut down until July 21 to "test mechanical and automated systems," according to Russian gas company Gazprom.
But the shutdown has a number of European Union countries worried that the closure will extend beyond its 10-day maintenance timeline as much of Europe rebukes Russia's war in Ukraine.
"We cannot rule out the possibility that gas transport will not be resumed afterward for political reasons," Klaus Mueller, Head of Germany's energy regulator told CNBC last week.
A number of European countries have been filling underground storage with natural gas supplies to make sure there is enough fuel for the winter. Germany, Italy, Austria and the Netherlands are prepared to use coal-fired plants to make up for any new gas shortages, their leaders have said.
If supply "doesn't come back after maintenance because President [Vladimir] Putin plays games or wants to hit Europe while it hurts, then the plan to fill up gas storage by the end of the summer will probably not work," Henning Gloystein, director of energy, climate and resources at Eurasia Group told CNBC.
French Finance Minister Bruno Le Maire told a business conference in southern France a total cutoff is "the most likely scenario."
France relies on Russia for 17% of its fuel, while Germany gets 35% of its energy supplies from Russia, numbers that declined after the Kremlin cut its output last month over a maintenance issue. Germany is bracing for the worst as new maintenance begins and has warned consumers to start conserving.
Over the weekend, Germany convinced Canada to return a Siemens Energy turbine, needed for the Nord Stream pipeline in time for this week's maintenance, over concerns Russia could use that as an excuse to delay gas flows.
While the United States late Monday issued a statement in support of the move, it has been criticized by the Ukrainian government, which called it "energy blackmail."
"This dangerous precedent violates international solidarity, goes against the principle of the rule of law and will have only one consequence," Ukraine's foreign and energy ministries said in a statement. "It will strengthen Moscow's sense of impunity."
In his nightly address Monday, Ukrainian President Volodymyr Zelensky announced that the ministry of foreign affairs had summed Ottawa's envoy over the decision, one he called "an absolutely unacceptable exception to the sanctions regime against Russia."
"If a terrorist state can squeeze out such an exception to sanctions, what exceptions will it want tomorrow of the day after tomorrow?" Zelensky asked.
Seemingly in defense of its ally, the U.S. State Department said in a statement late Monday night the turbine will allow Germany and other European countries to replenish their gas reserves, which will increase their energy security and resilience to counter "Russia's efforts to weaponize energy."
"At the same time, we are taking active steps to limit the impact of President Putin's war on global energy markets and protect our economies," State Department spokesman Ned Price said.
German ambassador to Canada, Sabine Sparwasser, also thanked Canada for the turbine while re-committing to support Ukraine "on all levels."
"We know it was not easy. But it is crucial to help Canada's European allies to steadily build out our independence from Russian energy," she tweeted.