A civilian cargo ship sailing from Ukraine reached Istanbul on Thursday in defiance of a Moscow blockade that sent tensions soaring after Russia open fired on a Turkish-owned ship.
The Hong Kong-flagged Joseph Schulte left the port of Odesa on Wednesday - the first vessel to directly challenge Russia's new bid to seal Ukraine's access to the Black Sea.
Marine traffic sites showed it approaching its final destination in Istanbul after moving along a western route that avoided international waters in favor of those controlled by NATO members Romania and Bulgaria.
Ukrainian President Volodymyr Zelenskyy said the ship was using a "new humanitarian corridor" Kyiv established after Russia last month pulled out of a wartime agreement to export grain along the Black Sea.
The Joseph Schulte's mission came days after the Russian navy fired warning shots and boarded a Turkish-owned but Palau-flagged vessel that was sailing to the Ukrainian river port of Izmail.
The Russian attack put immense pressure on NATO member Turkey to stiffen its officially neutral line in the war.
The Turkish presidency broke a four-day silence on Thursday by announcing that it had "warned" Moscow about the need to avoid further maritime escalations.
But the Turkish statement stressed that it was technically up to Palau - a Pacific archipelago often used as a "flag of convenience" by global shipping companies - to lodge a formal complaint.
Russia has stepped up attacks on Ukraine's shipping infrastructure since pulling out of the grain deal mediated by the U.N. and Turkey.
Ukraine's decision to confront Russia over sea access comes with world attention focusing on ways to secure grain export routes in time for this autumn's harvest.
Ukraine and Russia are major exporters of grain and seed oil.
New US push
Last year's grain agreement helped push down global food prices and provide Ukraine with an important source of revenue to fight the war.
Ukraine is now using the Danube River to ship out its grain.
Much of that traffic flows down the river and ends up reaching the Black Sea at Ukraine's border with Romania.
The Wall Street Journal reported that U.S. officials are holding talks with Turkey and both Ukraine and its neighbors about increasing traffic along the Danube route.
An unnamed U.S. official told the paper that Washington was "going to look at everything" - including the possibility of military support for the Ukrainian ships.
But a Turkish defense official appeared to push back against Washington's initiative on Thursday.
"Our efforts are focused on making the grain corridor deal active again," the unnamed defense official told Turkey's NTV television. "We are not working on other solutions."
Turkish President Recep Tayyip Erdogan hopes to meet Russian counterpart Vladimir Putin this month for talks focused on the Black Sea.
Erdogan has tried to use his good relations with Moscow and Kyiv to raise Turkey's diplomatic profile during the war.
Turkey hosted two early rounds of Ukraine peace talks and stepped up its trade with Russia while supplying Kyiv with arms.
Diplomatic 'counteroffensive'
Russia pulled out of the grain agreement after claiming that the pact had failed to fulfill the goal of relieving hunger across Africa and other famine-stricken regions.
The Kremlin has since asked Turkey to help Russia export its grain to African countries without any involvement from Ukraine.
African countries have become an important ally that Russia is using to counter its wartime isolation from the West.
Ukrainian Foreign Minister Dmytro Kuleba told AFP this week that Kyiv needed to launch a diplomatic "counteroffensive" on the continent.
"Our strategy is not to replace Russia but to free Africa from Russia's grip," Kuleba said in a wide-ranging interview.
Russia's attempts to win unilateral control of Black Sea shipping routes come as Ukraine inches forward in its high-stakes but brutal summer offensive.
Kyiv this week announced the capture of Urozhaine, a small village lying along one of Ukraine's main lines of attack.
Kyiv is trying to reach its southern coast and cut Moscow's access to Ukraine's Russian-seized peninsula of Crimea.
NATO row
The offensive is relying on new Western equipment and training but progressing slower than Kyiv and its allies had hoped.
The strength of Russia's resistance has intensified debates in some Western capitals about a need to find a diplomatic end to the war.
A top NATO official this week outraged Kyiv by suggesting that one possible solution to the war could involve Ukraine ceding territory in exchange for Kyiv's membership in the U.S.-led alliance.
NATO chief Jens Stoltenberg intervened on Thursday, reiterating the alliance's position that it was "up to Ukrainians, and Ukrainians alone, to decide when the conditions for negotiations are in place."
Kuleba insisted that Ukraine was "not feeling" pressure from its Western allies to demonstrate quick results.
"It's easy to say that you want everything to be faster when you are not there," he said.
