The Russian-flagged ship 'Nika Spirit' was detained by the Security Service of Ukraine (SBU) and the military prosecutors after it moored at the port of Izmail in southwestern Ukraine, according to the agency's statement. Ukrainian authorities have searched the vessel, seized her logs and communications records, as well as interviewed the crew.
SBU maintains that the tanker in question had blocked the passage of Ukrainian Navy ships through the Black Sea's Kerch Strait in November last year. Citing international maritime codes, the service said that she was allegedly called 'Neyma' at the time.
It is unclear what will happen to the ship and her crew, although SBU said it will seek an arrest order for the vessel. But the timing is particularly notable as the detention came amid low-key talks about the release of 24 Ukrainian sailors currently imprisoned in Russia.
Comment: This provocation is intended, obviously, to prevent their release and thus prevent rapprochement between the two countries.
On Wednesday, Ukrainian media cited Kiev's ombudsman, Lyudmila Denisova, who said that an agreement to return the sailors home has finally been reached. Later in the day, she refuted these reports, telling Russia's RBC newspaper that she only asked the FSB - the security agency in charge of trial - to release them under a bail scheme, and that talks are in progress.
All of them were manning fast attack crafts 'Nikopol' and 'Berdyansk', as well as the tug boat 'Yany Kapu', which tried to sail through the Strait and reach the Sea of Azov. The ships were stopped by the Russian coast guard and their crews were detained over the violation of maritime borders.
Later, Moscow accused Kiev of inflicting a provocation and revealed that the sailors have consciously ignored orders to change course, leaving the coast guard with no choice but to fire warning shots and ram the intruding vessels.
Ukraine, in turn, denied that its ships had violated Russia's border and insisted their crews' actions were lawful. Then-president Petro Poroshenko called the seizure of the ships "an act of aggression" and demanded that Moscow immediately release of the sailors.




Comment: When asked for further comment, the Ukrainian Ministry of Foreign Affairs stated: "Ooh-ooh, aah-aah, *grunt-grunt*..."
Here's video they published of the seizure:
UPDATE 28/07/2019: Russia slams Ukraine's 'act of piracy'. While the crew was released, Ukraine continues to hold the tanker itself.