By Jonathan Spicer and Ece Toksabay
ISTANBUL (Reuters) - Russia's raid on a ship just off Turkey's coast brings the fallout from the Ukraine war to another NATO frontier and raises the stakes as Ankara seeks to coax Moscow back to a grain-export deal that would restore some calm to the Black Sea.
Armed marines raided the Turkish-based vessel via helicopter on Sunday some 60 km (37 miles) off Turkey's northwest coast, in international waters but near Istanbul, in what Moscow called an inspection before it sailed on to Ukraine.
Turkey, NATO's second-largest military, has made no public comment on the incident that occurred far south of the war that has raged for a year-and-a-half in the north Black Sea.
Analysts said it tests President Tayyip Erdogan's resolve to maintain good relations with Russian President Vladimir Putin, whom he has invited to Turkey this month to discuss resuming the UN-brokered deal that had protected grain exports from Ukraine.
"This type of aggression being exercised so close to Istanbul went unchecked and doesn't respect Turkey's overall rights," said Yoruk Isik, an Istanbul-based geopolitical analyst at the Bosphorus Observer consultancy.
"Ankara's silence is strange but shows it is still counting on Putin to visit and return to the grain deal."
Since Russia exited the agreement last month, both it and Ukraine have issued warnings and carried out attacks on vessels off their coasts, stirring worries that commercial-shipping could grow riskier across the entire sea.
While Ukraine and some other Western states have promoted alternative routes for Ukrainian exports, Ankara, which also has good relations with Kyiv, quietly opposes them on safety grounds. It wants the West to accept some Russian demands, and for Russia to drop others, to restart Ukraine grain exports under UN and Turkish oversight.
On Wednesday, Russia struck more Ukrainian port facilities even as Kyiv announced that a container ship departed Odesa under its own "humanitarian corridor", one of the alternative options.
Rebeca Grynspan, Secretary-General of the United Nations Conference on Trade and Development, said on Wednesday it is in contact with all sides to return to the table though it was "difficult" partly given the recent bombardment of grain infrastructure.
FINE BALANCE
The Black Sea and Turkish straits are the main route Ukraine and Russia - two of the world's top agriculture producers - use to reach world markets.
Since the year-long grain deal collapsed, boosting global commodity prices and raising UN concerns over world hunger, Russia and Ukraine have said they will treat ships approaching the other's ports as potential military vessels.
Aydin Sezer, a former Turkish diplomat and Ankara-based foreign policy analyst, said Russia's inspection of the Palau-flagged Sukru Okan vessel technically took place in a war zone, given Moscow and Kyiv's warnings over ships.
Given Turkey has sent armed drones and other weapons to Ukraine while also claiming to be neutral in the war, "it is very challenging for Turkey to find its voice on this matter," he said.
Turkey has positioned itself to facilitate any peace talks between Ukraine and Russia. It has opposed the Russian invasion but also the Western sanctions on Moscow, and ramped up economic cooperation with Russia through the war.
A Turkish defence ministry official, requesting anonymity, said Ankara was looking into the Black Sea raid but gave no more details. The vessel has since sailed on to Romanian waters, according to Refinitiv Eikon data.
Russia has not commented on a potential visit by Putin, though Turkey has promoted it repeatedly including in a leaders call on Aug. 2.
Russia has said it would return to the grain deal once the West fulfils obligations meant to ensure the smooth export of its own grain and fertilisers, including payments and logistics.
Sezer said its two key demands are including a Russian bank in the global SWIFT payments system and allowing it to import agriculture-related goods.
"Therefore Erdogan should negotiate and try to convince Western countries, not Putin, for the reinstatement of the grain deal," he said.