Europe is bracing for an extended shutdown of Russian gas supplies as maintenance work begins on the Nord Stream 1 pipeline that brings gas to Germany via the Baltic Sea.

Operator Nord Stream AG confirmed the work, which is scheduled to run from Monday through to July 21, got underway as planned Monday morning. Russian gas flows via the pipeline are expected to drop to zero later in the day.

Europe fears the suspension of deliveries could be extended beyond the 10-day timeline, derailing the region’s winter supply preparations and exacerbating a gas crisis that has prompted skyrocketing energy bills for households and emergency measures from policymakers.

It comes as European governments scramble to fill underground storage with gas supplies to provide households with enough fuel to keep the lights on and homes warm during winter.

The EU, which receives roughly 40% of its gas via Russian pipelines, is trying to rapidly reduce its reliance on Russian hydrocarbons in response to President Vladimir Putin’s monthslong onslaught in Ukraine.

Klaus Mueller, the head of Germany’s energy regulator, believes the Kremlin may continue to throttle Europe’s energy supplies beyond the scheduled end of the maintenance work.

Energy analysts agree that the risk of a temporary interruption is high, particularly as Russian gas flows have already dropped by about 60% in recent months.

Russia’s state-backed energy giant Gazprom has cited the delayed return of equipment serviced by Germany’s Siemens Energy in Canada for its reduced flows.

Canada said over the weekend that it would return a repaired gas turbine back to Germany for use in the Nord Stream 1 pipeline, while also expanding the sanctions against Russia’s energy sector.

Russia said last week that it would increase gas supplies to Europe if the turbine being serviced in Canada was returned. Kremlin spokesperson Dmitry Peskov also dismissed claims that Russia was using oil and gas to exert political pressure over Europe, Reuters reported.