Reliance on a single source or a single transportation route can pose a danger to supplies, whether because of a technical accident or political andeconomic disputes such as the ones between Russia and Ukraine - a transit country for Russian gas to the EU - over energy prices in 2006 and 2009 that disrupted supplies to several European countries.

Following this crisis, the EU strengthened in 2010 its rules for security of gas supply by obliging member states to ensure that gas is supplied to households and other vulnerable customers such as hospitals, even under demanding conditions such as a disruption of main gas infrastructure. In 2014, the European Commission conducted so-called gas stress tests that showed that Europe could cope with gas supply disruptions only if member states cooperated more.

Last year it proposed to update the 2010 regulation by introducing a new solidarity mechanism that would ensure that a member state that declares an emergency level could receive gas from neighbouring countries. In April Parliament and Council negotiators reached an agreement on the text that was approved by MEPs on 12 September.