Showing Istan-bullies middle finger as they pass by
It's an occasional but regular sighting in Istanbul. Out of the mist on the Bosphorus that divides Europe and Asia looms the hulk of a Russian warship purposefully making its way to the Mediterranean.
Most likely the ship is part of Moscow's so-called "Syria Express", a key supply line for naval deliveries from its Black Sea ports to military operations backing the regime of President Bashar al-Assad in Syria.
Dozens of Russian warships, auxiliary naval cargo ships and sometimes even submarines have passed through the Bosphorus Strait, northbound and southbound. Every month since Russia stepped up operations inside Syria last year, according to maritime experts.
But the sight of a Russian warship in Istanbul is striking given that Moscow and Ankara are experiencing their worst relations since the end of the Cold War after the shooting down of a Russian warplane by Turkish jets on the Syrian border on November 24.
The two countries back opposing sides in Syria's almost five-year civil war, with Russia the key supporter of the Damascus regime while Turkey argues that the ouster of Assad is essential to solving the Syrian crisis.
Analysts say that Turkey is bound by the 1936 Montreux Convention on the Dardanelles and Bosphorus, a treaty that gives Ankara full control over the two Straits while committing it to allowing the free passage of naval traffic from Black Sea littoral states.
Under its terms, Turkey can only block Russian naval shipping if war is declared or if it feels under an imminent threat of war.
"Since there is no declared war between these two countries it is not possible for Turkey to close the Straits to Russian warships," said Cem Devrim Yaylali, Istanbul-based Turkish naval expert and editor of the Bosphorus Naval News website.
He said that even "in the worst days of the Cold War" -- pitting NATO member Turkey against the Soviet Union -- Ankara and Moscow both observed the treaty.
Mikhail Voitenko, Russian maritime expert and editor of the Maritime Bulletin website, said that the supplies delivered via the Bosphorus were a "lifeline" for the Syria campaign.
"Without the Syrian Express, the Syrian campaign would choke in days or weeks."