Russia and Turkey have put aside differences on regional issues to forge strong economic ties.
In December, they finalized an agreement for Turkey to buy Russia's missile defense system. The deal raised eyebrows among Turkey's NATO allies.
Besides military purchases, the two countries are also building the "Turkstream" pipeline, to transport Russian gas to Turkey.
In response to the poisoning in Britain of a former Russian spy, Turkey said it won't follow its NATO and EU allies in ousting Russian diplomats. Ankara condemned the attack without naming Russia, adding that it enjoyed positive relations with Moscow.