Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan inaugurated a new gas pipeline linking their countries, at a ceremony in Istanbul on Wednesday with tensions over Libya and Syria also on the agenda.
Erdogan described the Turkstream pipelines — which will deliver Russian gas to Turkey and Europe via the Black Sea — as a "project of historic importance" for relations between their countries.
Turkey did not allow divergence in opinions with Russia to derail common interests, Erdogan also said.
During his speech, Erdogan ruled out any project in the Eastern Mediterranean excluding Turkey.
"There is no chance of realising any project in the Eastern Mediterranean that excludes our country …," he said.
Last week, Greece, Israel, and the Greek Cypriot Administration signed a controversial deal for the EastMed project to build a 1,900-km natural gas pipeline that will run from Israel through Southern Cyprus, Crete, Greece and ultimately to Italy, a plan Turkey says is bound to fail.
The pipeline was a sign of "interaction and cooperation for the benefit of our people and the people of all Europe, the whole world," Putin said at the inauguration ceremony.
"I am sure that in the future Russia and Turkey will implement many more mutually beneficial projects both in energy and other areas," he said.
There are tendencies to raise tensions in the region but Turkey and Russia aim at the opposite, the Russian president stressed.
Putin arrived late on Tuesday after paying a surprise visit to Syria — his first to Damascus since the war began — at a moment of acute uncertainty in the Middle East following the killing of top Iranian general Qasem Soleimani by the United States.
TurkStream and the Nord Stream pipelines under the Baltic allow Russia to increase gas supplies to Europe without having to rely on Ukraine.
But Moscow's increasing domination of European energy markets has worried the United States, which last month sanctioned firms working on TurkStream and the almost-completed Nord Stream 2.
The ceremony in Istanbul reflected a dramatic improvement in ties between Russia and Turkey with both sides hailing the cooperation.
Turkey and Russia have established a regular dialogue over the Syrian conflict, despite being on opposing sides, but now find their relations tested again in Libya.
Last week, Turkey sent its first troops to help defend the UN-backed Tripoli government, which is under siege from warlord Khalifa Haftar.
Erdogan has underlined that the deployment remains small for now: only 35 soldiers and limited to training and coordination roles, according to comments carried in the Hurriyet newspaper.
He has criticised the presence of 2,500 Russian mercenaries supporting Haftar — claims denied by Moscow.
Russia so far seems unfazed by the Turkish deployment in Libya, said Mariana Belenkaia, of the Carnegie Centre in Moscow.
"The two countries will likely be tempted to share the Libyan burden," she said.
Syria remains a potential powder keg for Erdogan and Putin's relationship.
Syrian regime forces — backed by Russia — have ramped up bombardment of the last opposition strongholds in Idlib province in recent weeks, sending hundreds of thousands fleeing towards the Turkish border.
Erdogan has called for a ceasefire in Idlib, following previous temporary halts to the fighting brokered with Russia in late 2018 and updated in August last year.
Improved ties between the two countries have been facilitated by a number of major energy and defence deals.
Russia is building Turkey's first nuclear plant and last year delivered the S-400 missile defence system, to the consternation of Turkey's NATO allies.
Putin earned goodwill in Turkey after his quick support for Erdogan following an attempted coup in July 2016.
The two men have developed a "strong personal relationship," according to Jana Jabbour of Sciences Po university in Paris, who adds that "their economic and energy plans are interdependent."
The TurkStream project, which was temporarily halted during a frosty patch in Russia-Turkey relations, includes two parallel pipelines of more than 900 kilometres.
The pipeline links Anapa in Russia to Kiyikoy in northwestern Turkey and has already begun deliveries to Bulgaria. It is being extended towards Serbia, Hungary and Austria.
The pipeline has a total capacity of 31.5 billion cubic metres, out of which the first line will carry 15.75 billion cubic metres of Russian gas to Turkish consumers.
The second line will carry another 15.75 billion cubic metres of gas to Europe via Turkey.
BOTAS built the first line that will connect to Turkey’s existing gas grid, while the second line, to be operated by a Gazprom-BOTAS joint venture, will stretch to the Turkish-European border in Turkey's Thrace region.