It is unclear what the facts are. I do not understand the difference between  vessel registration and the flag it is under. Apparently an oil tanker was headed to Russia and was in international waters but in the Estonian economic zone. Estonian warship asks the tanker to divert to an Estonian port and the tanker refused. A Russian jet came out and the Estonian warship went away.

I asked Grok some questions at the end. IMO FAFO.

https://x.com/MyLordBebo/status/1922721452874154413
https://x.com/i/status/1922721571031953718   video clip

Here is the Estonian officials' description of the incident - for full context.

**Estonian Defense Forces Chief of Staff: No Plan to Board Non-Compliant Shadow Fleet Tanker Jaguar**

Major General Vahur Karus, Chief of Staff of the Estonian Defense Forces, told *Aktuaalne Kaamera* that Estonia had no intention of boarding the shadow fleet tanker *Jaguar*, which did not comply with orders. He noted that Tuesday's incident marked the first time the Russian Air Force actively took a defensive stance in relation to a shadow fleet vessel.

Karus explained the sequence of events on Tuesday when a Russian shadow fleet vessel entered Estonia's economic zone, failed to comply with orders, and was escorted by Russian Air Force planes, one of which violated Estonian airspace.

On Tuesday morning, the tanker *Jaguar* was detected moving toward Estonia, suspected of lacking a flag state. "It was registered in the Russian Federation. We began monitoring it, made inquiries to various countries, and confirmed that the vessel indeed had no flag state," Karus said.

Initially, the vessel claimed to have a Guinea-Bissau flag, which had been revoked. The crew then stated it was flagged under Gabon, but Gabonese authorities confirmed that since May 10, after the vessel was sanctioned by the United Kingdom, they had withdrawn its flag state status.

Around 6:30 p.m., the tanker entered Estonia's economic zone near Naissaar. "The Navy began hailing it to determine the vessel's status and verify its flag state. The intent was to direct it to an anchorage area to check its flag state, insurance, and compliance with maritime conventions," Karus explained.

During the hailing, the Russian Air Force joined with two aircraft, Karus said. "During this so-called shadowing, which lasted 2.5 hours, a Russian aircraft violated Estonian airspace," he added.

**Russian Fighter Jet's Airspace Violation Coincided with Tanker Escort** 
According to the Foreign Ministry, the airspace violation occurred around 9:00 p.m.

By 11:00 p.m., the vessel left Estonia's economic zone and entered Russian waters. "That concluded the matter for us," Karus noted.

When asked if this was the first time the Russian Air Force had actively defended a shadow fleet vessel, Karus replied: "Clearly, that's how we see it. This is the first time Russia has taken such an overtly protective stance toward a vessel."

However, he acknowledged that, apart from the airspace violation, the Russian Air Force acted professionally. "There were no low flyovers; they maintained a constant patrol above the vessel," Karus said.

Karus stated there was no reason to board the vessel. "It was a deliberate decision made during our planning," he said.

He added that, in addition to a helicopter, other air assets were deployed, including Portuguese F-16s from Ämari airbase providing air policing. "When Russia sent its aircraft, our air policing unit immediately took off to identify who we were dealing with," he explained.

**Delayed Public Disclosure** 
When asked why information about the incident only reached the public on Wednesday evening via Polish media, Karus said: "We don't publicize many things, and we cannot comment on ongoing operations."

Karus described the media leak as manipulation rather than a Russian information operation. "It has all the hallmarks—considering how it was filmed, what was filmed, and how quickly Russian outlets began spreading it. I'd call it media manipulation," he said.

According to the latest information, the *Jaguar* was not allowed to enter a Russian port and is currently at a temporary anchorage.

**Editor**: Valner Väino 
**Source**: *Aktuaalne Kaamera*, interviewed by Maria-Ann Rohemäe

GROK says
Legal Framework and Justification
The primary legal justification for the Estonian navy's actions, as stated by Estonian Naval Commander Ivo Vark in a report by Reuters, was that the JAGUAR was sailing "without a nationality." This refers to the vessel not displaying its flag, a requirement under the United Nations Convention on the Law of the Sea (UNCLOS). Specifically:

...
    UNCLOS Article 110 allows a warship to board a foreign ship on the high seas if it is without nationality, providing a legal basis for interception in such cases.

Given that the JAGUAR was reported to be near Naissaar Island, approximately 8 km north of Tallinn, it was within Estonia's territorial waters (up to 12 nautical miles from the baseline) or its exclusive economic zone (EEZ, up to 200 nautical miles). Within these zones, Estonia has sovereign rights and jurisdiction to enforce laws related to maritime safety, security, and resource protection. The failure to display a flag would justify contacting the vessel by radio to verify its status, aligning with international maritime law.
...

Given Naissaar's proximity to Tallinn (approximately 8 km, well within 12 nautical miles), it is likely within Estonia's territorial sea, where full sovereignty applies. In the EEZ, Estonia has rights over resource-related activities but less authority over navigation, yet the stateless vessel rule under UNCLOS would still apply for boarding purposes.
...
This incident follows a pattern, as seen with the Estonian navy's detention of the tanker Kiwala on April 11, 2025, reported by Reuters. The Kiwala was detained for sailing without a valid flag and being on an EU sanctions list, reinforcing the legal basis of flag violations in such operations.
...
Grok says
On April 11, 2025, the oil tanker Kiwala, suspected to be part of Russia's "shadow fleet" used to circumvent Western sanctions, was detained by the Estonian Navy in the Baltic Sea near Tallinn. The vessel, en route from Sikka, India, to the Russian port of Ust-Luga, was intercepted in Estonia's Exclusive Economic Zone in the Gulf of Finland for operating without a valid national flag, a violation of maritime law. The Kiwala was reportedly flying a Djibouti flag, but Djibouti authorities denied it was registered with them. Estonian authorities, supported by a helicopter, naval ships (Kindral Kurvitz and Admiral Kovan), and border guard vessels, forced the tanker to enter Estonian territorial waters and anchored it in Muuga Bay, east of Aegna Island, for inspection.
The Estonian Transport Administration identified 40 deficiencies during an inspection, including 23 documentation issues and others related to the ship's technical condition, safety management, and crew preparedness. The vessel, owned by Mauritius-based Tirad Shipping and operated by a Hong Kong company, was under sanctions from the EU, UK, Canada, and Switzerland for prior illicit activities. The crew, consisting of 24 third-country nationals (including a Chinese captain and mostly Myanmar citizens), cooperated with authorities.
Estonian officials detained the Kiwala to verify its legal status and ensure maritime and environmental safety, citing concerns about unregulated shadow fleet vessels posing risks to navigation and infrastructure. The operation was not linked to suspected damage to undersea cables, despite regional concerns about Russian sabotage. The tanker remained under guard by Estonian naval vessels until April 26, 2025, when it was released after resolving the identified deficiencies, allowing it to continue its journey to Ust-Luga.


Grok says
In summary, due to the gulf's geography and the extent of territorial waters, any vessel traveling to St. Petersburg must pass through either Estonian or Finnish territorial waters, typically under the regime of innocent passage.

More grok
Grok says

If a vessel is in Estonian territorial waters in the gulf of finland, can estonia board such a vessel?


Yes, Estonia has the authority to board a vessel in its territorial waters in the Gulf of Finland,...

If a vessel is in Estonian territorial waters, Estonia can board it for several reasons, including:...

Maritime Law Violations: Estonia can board a vessel to enforce compliance with maritime regulations, such as verifying registration, safety standards, or environmental protections. For example, in the case of the tanker Kiwala on April 11, 2025, Estonia boarded the vessel after detaining it for operating without a valid flag, a serious violation of maritime law.

...
Sanctions Enforcement: If a vessel is suspected of violating international sanctions (e.g., EU sanctions on Russia, as with shadow fleet vessels), Estonia can board to verify its cargo, ownership, or activities.
...
if such a vessel is violating EU sanctions what can be done with the vessel?


In summary, if a vessel in Estonian territorial waters violates EU sanctions, Estonia can board, inspect, detain, fine, seize, or ban the vessel, pursue legal action against its owners, or refer the case to EU/international authorities. The specific response depends on the violation's nature and severity, balanced by legal and diplomatic considerations.
...

please explain the legal basis for enforcing EU sanctions against the vessel of a sovereign state?



Within territorial waters, Estonia can enforce its laws and regulations, including those implementing EU sanctions, on any vessel, regardless of its flag state.

...
The European Union has established a robust legal framework for imposing and enforcing sanctions, which member states like Estonia are obligated to implement.


...
Council Regulation (EU) No 833/2014 (as amended) imposes restrictions on Russia, including prohibitions on importing certain Russian goods (e.g., crude oil above the G7/EU price cap), providing services (e.g., insurance or financing) to sanctioned vessels, and engaging with entities involved in sanctions evasion.


...
Estonia's International Sanctions Act provides the legal basis for enforcing EU and international sanctions within its territory, including territorial waters.

The Act authorizes Estonian authorities (e.g., Police and Border Guard Board, Navy, Transport Administration) to take measures like boarding, detaining, or seizing vessels involved in sanctions violations.


...
Grok says
Can Finland and Estonia act to close the Gulf of Finland to vessels violating EU sanctions?


Yes, Finland and Estonia, as coastal states bordering the Gulf of Finland and EU member states, have the legal authority to take actions that could effectively restrict or control access to the Gulf of Finland for vessels violating EU sanctions. However, "closing" the Gulf of Finland entirely to such vessels is a complex matter involving legal, practical, and diplomatic considerations. Instead of a complete closure, Finland and Estonia can implement targeted enforcement measures to deter, intercept, or deny passage to vessels violating EU sanctions.


Council Regulation (EU) No 833/2014 (as amended):
This regulation imposes restrictions on Russia, including bans on importing certain goods (e.g., crude oil above the G7/EU price cap), providing services (e.g., insurance) to sanctioned vessels, and engaging with entities involved in sanctions evasion.

...
Port Bans and Vessel Lists:
The EU can ban vessels involved in sanctions violations from entering EU ports or waters. For example, the tanker Kiwala, detained by Estonia on April 11, 2025, was under an EU port ban for prior sanctions violations.

Finland and Estonia can enforce these bans by denying entry or detaining listed vessels.
...

UNCLOS guarantees innocent passage for vessels not engaged in prohibited activities. A blanket closure of the gulf to all vessels, even those suspected of violations, would violate international law unless justified by exceptional circumstances (e.g., a UN Security Council resolution or a state of emergency).

Targeted enforcement (e.g., inspections or detentions) is legally permissible, but a total blockade would require broader international support.


...
6. Could Finland and Estonia "Close" the Gulf?
A complete closure of the Gulf of Finland to vessels violating EU sanctions is not feasible under current international law, as it would infringe on innocent passage and require a legal basis like a UN Security Council resolution or a declared maritime exclusion zone (rare outside wartime). However, Finland and Estonia can achieve a similar effect by:
Systematically inspecting and detaining violating vessels in their territorial waters.

Denying passage to vessels engaged in non-innocent activities.

Banning sanctioned vessels from EU ports and waters.

Coordinating patrols to deter shadow fleet operations.

Such measures would make the gulf highly risky and costly for sanctions-violating vessels, effectively discouraging their transit without a formal closure.


...