The Russian navy opened fire on a cargo vessel in the Black Sea to force it to stop for checks, the defense ministry said, the first such confirmed incident since Moscow withdrew from a key grain export deal in July. 

The dry freight vessel Sukru Okan, sailing under the flag of Palau, had been heading to Ukraine’s port of Izmail when the naval patrol ship Vasiliy Bykov came across it in the southwestern part of sea early Sunday morning. 

The navy ordered the vessel to stop for inspection and when the operators of the Sukru Okan didn’t respond, opened fire, Russia’s ministry said. 

When the vessel finally stopped, Russia sent a group of soldiers in a helicopter to board it for inspection. They later allowed the ship to resume its journey to Ukraine, the ministry said, without elaborating what cargo — if any — it was carrying. 

Russian President Vladimir Putin in July let lapse the agreement, brokered by Turkey and the UN, that allowed the safe passage of vessels exporting Ukrainian grains and other foodstuffs from ports near Odesa. 

The defense ministry at that time said that all ships headed to Ukraine’s ports would be considered as potentially carrying military cargo. Ukraine made similar comments as the situation in the Black Sea — which is bordered by six countries — turned increasingly tense.

Since then, Ukraine drones crippled a Russian naval vessel and an oil tanker, putting Russian commodity exports via the Black Sea at risk for the first time. Russia has repeatedly targeted grain-export infrastructure in Odesa and beyond with missile strikes.  

Kyiv has said that it wants to reopen the trade routes despite the Kremlin’s threats. Most shipowners are wary of sending vessels and crews into harm’s way, though, while insurers view Ukraine’s ports as unsafe without the protection of the grain deal. 

Ukraine has laid out temporary Black Sea routes for ships that are willing to navigate waters threatened by Russia.