The new pipeline will transport 31.5 billion cubic metres of gas from Russia to Turkey and on to Eastern Europe per year.
The Turkish and Russian presidents are meeting in Istanbul to inaugurate the dual natural gas line connecting their countries that will open up a new export path for Russian gas into Turkey and Europe.
Presidents Recep Tayyip Erdogan and Vladimir Putin are also expected to discuss Syria and Libya, where the two leaders support opposing sides while addressing regional tensions in Iraq and Iran, which have escalated with the American killing of a top Iranian commander.
With TurkStream, Russian gas will pass through the Black Sea to Turkey. Together, the two 930-kilometre (578-mile) lines under the Black Sea, along with the Russian and Turkish onshore pipes, will have the capacity to carry 31.5 billion cubic metres (1.1 trillion cubic feet) of natural gas annually.
Russia is the top gas supplier to Turkey, which relies on imports for its energy needs, transporting gas through another pipeline under the Black Sea called Blue Stream and the onshore West Line through Ukraine. Relations remain tense between Moscow and Kyiv with years of conflict and TurkStream allows Russia to bypass Ukraine by opening up a second direct transport line to Turkey.
From Turkey, Russian gas will reach southern and southeastern Europe through new and existing lines.
Erdogan and Putin talk and meet often, cooperating on trade, energy and defence industries while engaging in negotiations on the Syrian civil war and now also on Libya.
Backed by Russia, the Syrian government’s all-out offensive to retake Idlib —the last rebel-held stronghold in Syria— has pushed hundreds of thousands of civilians towards the closed Turkish border, risking a major new refugee flow to Turkey.
Putin is in Turkey following a visit to Syria where he met President Bashar Assad. Turkey has supported rebels opposing Assad in the country’s eight-year civil war.
War-torn Libya is now another location where the two leaders will try their diplomatic influence and negotiations. Turkey has moved to send Turkish soldiers and weapons to support the weak U.N.-recognised Tripoli-government while Russia has backed the rival eastern-based forces of General Khalifa Hafter.