Cormoran (P677), a French navy ship. Brest, Finistère, Bretagne, France. Photo by Gary Houston
I really would like to know the basis of this seizure: French Navy Flamant-class OPV Cormoran seizes Russian cargo ship.
And then there are these seizures of Ukrainian flag ships by the Russians: Russian Navy seized two Ukrainian civilian vessels near Snake Island. If one or both of these ships was seized in Romania’s territorial sea, it would be a violation of international law
Chuck Hill's CG Blog 
The Russian freighter Baltic Leader seized by France is claimed to be owned by a Russian bank that was placed under sanctions by the USA a while ago. The European Union aligned its sanction regime recently, and the ship was thus seized while still in national waters after leaving a French port.
Russia claims that the ship was sold by the bank to a third agency before the sanctions started, and thus should not be affected by them.
Aljazeera report https://www.aljazeera.com/news/2022/2/26/france-seizes-russian-cargo-ship-targeted-by-us-sanctions?fbclid=IwAR0HPaP2OL5Jw8TpUbTesggeEdg_16hRCZZlej1NaLZ3-_CJWoH6sBcsxOA
Similar report here, but includes photo of the ship, https://www.marineinsight.com/shipping-news/cargo-vessel-suspected-of-russian-connections-captured-by-france/?awt_a=9oCv&awt_l=EgamK&awt_m=3ai4SXgvMkcctCv
Flashpoint at sea have a history, NATO’s Black Sea Border
https://blog.usni.org/posts/2022/03/02/natos-black-sea-border
German authorities seize $600m yacht of Putin-linked billionaire Alisher Usmanov https://www.msn.com/en-us/news/world/german-authorities-seize-600m-yacht-of-putin-linked-billionaire-alisher-usmanov/ar-AAUxfKw?ocid=msedgntp
Attorney General Merrick B. Garland Announces Launch of Task Force KleptoCapture https://www.globalsecurity.org/wmd/library/news/russia/2022/03/russia-220302-doj01.htm?_m=3n%2e002a%2e3268%2ejj0ao001ud%2e311i
“All You Need To Know About Russian Yacht Arrests” https://gcaptain.com/all-you-need-to-know-about-yacht-seizures/
Russian yacht seizures by the US could provoke a legal nightmare https://www.businessinsider.com/us-seize-yachts-sanctions-putin-russian-oligarchs-legal-practical-problems-2022-3?amp
Russian Project 22160 patrol ship Vasily Bykov reportedly damaged http://www.navyrecognition.com/index.php/naval-news/naval-news-archive/2022/march/11482-russian-project-22160-patrol-ship-vasily-bykov-reportedly-damaged.html
Post on the project 22160 here: https://chuckhillscgblog.net/2016/02/18/project-22160-patrol-ships-russias-cutter-x/
Attack on Bangladesh flag ship. One dead in attack east of Odesa. https://www.marinelink.com/news/two-cargo-ships-hit-blasts-around-ukraine-494750
Efforts to evacuate mariners from Ukraine. https://gcaptain.com/ukraine-seafarers-cost-of-war/
Panama reports three Panamanian flag ships hit by Russian missiles. Notably while one sank, the other two are still afloat and their have been no personnel casualties. https://www.marinelink.com/news/panama-says-three-ships-hit-russian-495120
Relative to the reports of mines floating in the Black Sea.
https://www.navalnews.com/naval-news/2022/03/opinion-is-there-a-serious-sea-mine-threat-in-the-black-sea/ and https://cimsec.org/new-heights-of-russian-hypocrisy-and-unlawfare-in-the-black-sea/
Merchant ships trapped in Ukrainian ports. https://www.marinelink.com/news/ships-stranded-ukraine-conflict-slows-un-495398
Small merchant ship hit by missile. One crewman injured. https://www.marinelink.com/news/foreign-merchant-ship-hit-missile-495582
Drone strike destroys LCU and its embarked AAW system, followed by SU-27 strike on Snake Island. https://www.navalnews.com/naval-news/2022/05/russian-serna-class-lcu-becomes-the-new-victim-of-tb2-drone/
Ukraine reports they have destroyed to more small Russian patrol boats using missiles launched from a UAV. http://www.navyrecognition.com/index.php/naval-news/naval-news-archive/2022/may/11716-ukrainian-navy-destroys-two-more-russian-patrol-boats-with-bayraktar.html
The Russians are trying hard to fortify and resupply Snake Island.
The Ukrainians are making them pay a high price for their efforts.
The susceptibility of these small craft to UAVs is on full display.
“Ukrainian Navy Ship In Dramatic Escape, Survives Russian Artillery Attack” https://www.navalnews.com/naval-news/2022/06/ukrainian-navy-ship-in-dramatic-escape-survives-russian-artillery-attack/
Reportedly the Ukrainians have sunk a large ocean going tug, hitting it with two Harpoon missiles. The vessel was reported to have embarked a TOR AAW missile system.
https://en.wikipedia.org/wiki/Tor_missile_system#2022_Russo-Ukrainian_War
Ukraine attacked a Russian occupied offshore oil facility. Additional attack on Snake Is. reported.
https://www.thedrive.com/the-war-zone/ukraine-attacks-russian-oil-platforms-snake-island-strike-rumors-swirl