Despite a regional rivalry that goes back to the Ottoman Empire and the Romanov dynasty, Russia and Turkey have been working closely since a 2016 reconciliation ended a crisis caused by the shooting down of a Russian war plane over Syria.
"Russia and Turkey are cooperating very tightly," Putin's spokesman Dmitry Peskov said ahead of the one-day working visit by Putin to Ankara.
Erdogan welcomed Putin at the doors of his vast presidential palace in Ankara for the evening talks, shortly after the Russian president landed at the city's airport.
Turkey and Russia have been on opposing sides during the more than six years of war in Syria, with Russia the key backer of President Bashar al-Assad and Turkey supporting rebels seeking his ouster.
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But while Turkey's policy is officially unchanged, Ankara has notably cooled its attacks on the Damascus regime since its cooperation with Russia began to heat up.
Both Moscow and Ankara are pushing for the creation of four "de-escalation zones" in Syria, in line with peace talks in Astana, to end the civil war that has raged since 2011.
Turkey, a NATO member, has signed a deal reportedly worth USD 2 billion to buy S-400 air defence systems from Russia, a move that has shocked its allies in the alliance.
Economic cooperation is also beginning to flourish, with Russian tourists returning to Turkey and the two countries working on a Black Sea gas pipeline.
Yet analysts say that while both countries share an interest in seeking to discomfort the West by showing off close cooperation, their relationship falls well short of a sincere strategic alliance.
Russia's stance on the non-binding Kurdish independence vote is also troubling for Turkey, for whom opposing Kurdish statehood is a cornerstone of foreign policy due to its own Kurdish minority.
The Russian foreign ministry said Wednesday that while Moscow supports the territorial integrity of Iraq, it "views the Kurds' national aspirations with respect".
"Russia has been trying to abstain from taking a clear stance on the issue and Turkey may be wanting to get some assurances and explanations," Timur Akhmetov, Ankara-based Turkey expert at the Russian International Affairs Council, told AFP.
Deliveries of the S-400s, meanwhile, could be years away due to orders from China, while Ankara's insistence on a technology transfer as part of the deal may also create problems.
But both Moscow and Ankara are, for now, happy to send a message to the West that they are serious about defence cooperation.
"They are trying to utilise the issue of the S-400 for their respective political interests," Akhmetov told AFP.