Russia shut down the supply of natural gas to Europe on Monday to carry out scheduled maintenance, raising fears in Europe of a possible extended shut down by Russia in response to sanctions, which could cause an energy crisis.

Start of maintenance work on Nord Stream 1

There are pipe systems and shut-offs at the gas receiving station.

dpa/picture alliance via Getty Images

Repairs are scheduled to take place over the course of the next 10 days, which will cause the Nord Stream 1 to be shut down.

According to Klaus Muller, the head of Germany's energy regulator, gas supply via theNord Stream dropped to zero on Monday.

Muller notes that any potential delay will not be known a day before the deadline.

European officials are worried that Russia may deliberately delay the restart of gas supplies in order to punish western Europe for its sanctions against Moscow.

A majority of 40%. As Russia moved to cut supplies, the capacity at which theNord Stream 1 pipe was operating was reduced. The equipment issues that couldn't be fixed due to sanctions were the reason for the drop.

Tangent

After intense lobbying by Germany, Canada agreed to an exemption in its sanctions against Russia to allow for the export of a critical piece of equipment that is expected to help resolve equipment issues on the line. The Ukrainian government said that it would encourage Moscow to use natural gas in order to get concessions from the West.

The second phase of Germany's gas emergency plan was triggered last month due to the drop in Russian gas supplies. The German federal government warned about an increase in gas prices and urged citizens to cut back on gas use. Robert Habeck, the German economics minister, accused Putin of carrying out an economic attack on Germany. Habeck warned of potential industry shutdowns and job losses if gas reserves run low in the winter and said that a further slump in supplies from Russia could cause a 2008 Lehman Brothers-style collapse of Europe's energy sector. Russia has stopped the supply of gas to several European countries after they refused to use a rubles bank account.

What To Watch For

Germany needs to have its gas reserves up to 90 percent by the end of the year in order to have an emergency plan. The German government will have to take over the distribution of gas and rationing if it fails to do so.

Germany re-opens coal plants because of reduced Russian energy.

German Minister Warns of "catastrophic" industrial shutdowns and mass unemployment if gas crisis continues.