Romania’s Danube Flotilla and the Lessons of the Russian-Ukrainian War
by George Vișan
The Importance of the Danube to Romanian Security and Defense
Romania is a Danubian state. Before its emergence as “Romania” in 1859, the Principalities of Wallachia and Moldavia had been known to European chanceries as the Danubian Principalities. Romania’s prosperity, links with the West and the Black Sea, as well as its security, are partly due to the Danube, which forms the natural border between Romania and the Balkans.
in many respects, the Danube is as important to Central and Southeastern Europe as the Rhine is to Western Europe. After the Volga, it is the second-longest river in Europe, with a total length of 2,850 kilometers. Originating in the Black Forest of southern Germany, the Danube flows through Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova, and Ukraine before reaching the Black Sea. Of its total length, approximately 2,415 kilometers are navigable.
Romania is the European country through which the Danube flows for the greatest distance and contains most of its delta. The river runs for 1,075 kilometers through Romania—about 29% of its total course—forming parts of the country’s borders with Serbia, Bulgaria, Moldova, and Ukraine. All 1,075 kilometers of the Danube within Romania are navigable, including 235 kilometers of internal waters. The river segment between the ports of Brăila and Sulina is known as the maritime section, which can accommodate vessels with a draught of up to nine meters. Navigation on the Danube is possible a the present time for only about 280 days per year, which limits its full economic potential. However, the European Union’s Fast Danube 2 program, once implemented, is expected to extend navigability to approximately 340 days per year.
The main canals through which the Danube flows into the Black Sea are Chilia (partly shared with Ukraine), Sulina and Sfântul Gheorghe (Saint George). Sulina is the most important canal of the three, being the shortest route to the Black Sea. An alternate route is the Danube-Black Sea canal, built in the 1980s and is 95 kilometer (km) long which shortens the distance for freight, linking the ports of Constanța and Midia Năvodari to the lower course of the river, but compared to Sulina freight transit is limited by the lock system.
Map Source:
https://www.nytimes.com/2023/08/16/world/europe/ukraine-romania-danube-shipping.html
From a naval perspective, protecting the Danube is as important for Romania as safeguarding the littoral and the main sea lines of communication in the Black Sea. The Danube is also an important economic route, linking Romania to Central and Western Europe. Moreover, the mouths of the Danube—the three canals and the Danube Delta—are significant strategic points in the Black Sea, as they serve both as alternative routes into the sea and as entry points to the Balkans and Central Europe.
The strategic importance of the Danube and its link to the Black Sea has long been recognized by the empires that have shaped European history. The Roman Empire, for example, depended upon two main European rivers: the Rhine in the West and the Danube in the East. The Ottoman Empire reached the line of the Danube in the 14th century in the Balkans long before conquering Constantinople in 1453. After which, it wrestled control of the mouths of the Danube from the medieval Romanian Principalities during the rest of 15th century.
In the modern era, control of the lower course Danube was disputed between three empires: the Ottoman Empire, the Habsburg Empire (later known as the Austro-Hungarian Empire) and the Russian Empire. France and Britain occasionally arbitrated the clashes between these large continental empires over one of the most important entry points into the Balkans, the Black Sea and Central Europe as well as lucrative trading route. One of these arbitrations, the Paris Peace Treaty of 1856, which ended the Crimean War, marked the beginning of the Romanian modern state. During both World Wars, control of the Danube was central to securing Central and Eastern Europe, as well as the Balkans.
The strategic importance of the Danube as a critical trading route was confirmed once again in 2022 during the large-scale Russian invasion of Ukraine. Faced with Russia’s blockade and attacks on its Black Sea ports Kyiv shifted its trade through the Danube in a major geopolitical move, using part of the river delta it controls as well as Romania’s riverine ports and the Sulina Canal, which had to be upgraded in order to permit both day and night navigation.
Approximately 70% of Ukrainian grain exports in 2023 used the Danube and Romania’s Black Sea ports to reach international markets. The importance of the Danube—its canals and port infrastructure—has not been lost on Russia, which regularly targets Ukrainian ports along the river with kamikazee attack drones, which will be discussed in detail below.
The Mihail Kogălniceanu Danube Flotilla
To protect Romanian interests on the river, Romanian naval forces have long maintained a riverine division within their fleet. The Mihail Kogălniceanu Danube Flotilla represents the latest incarnation of this structure. The namesake of the unit, Mihail Kogălniceanu, was one of the founding fathers of Romania, a revolutionary and a modernizer. As foreign minister he was instrumental in gaining Romanian independence in 1878, by participating in the Russo-Ottoman War of 1877-1878. Kogălniceanu was also the first modern Romanian leader to understand the need for Romania to have access to the sea.
The Mihail Kogălniceanu Danube Flotilla’s primary missions include deterring illegal activities such as smuggling along high-risk river routes and safeguarding adjacent land areas. It also conducts surveillance of riverine communications, combats piracy and potential terrorist threats, gathers intelligence, and protects commercial navigation routes. Additional responsibilities include escorting and protecting commercial vessels, securing ports, supporting civilian authorities during emergencies, and destroying enemy vessels when necessary.
The Danube Flotilla’s chief role is to interdict enemy crossings, secure the flanks of Romanian forces, and provide naval fire and escort support for riverine and amphibious operations. It plays a vital role in joint missions, especially during river crossings, providing fire support and aiding ground forces in amphibious assaults and establishing military bridgeheads.
The headquarters of the Danube Flotilla is located in Brăila, at the start of the deep-water section of the river known as the Maritime Danube. To carry out its missions, the flotilla can deploy a range of capabilities, including river monitors, armored patrol gunboats, patrol boats, and minesweeping vessels. These are supported by various auxiliary units such as floating barracks, landing barges, tankers, tugboats, and smaller craft. For amphibious operations and missions in the Danube Delta, the 307th Marine Infantry Regiment “Heracleea” operates under the command of the Danube Flotilla.
Armament
Romania’s Danube Flotilla is the strongest riverine naval formation in Eastern Europe. Bulgaria, Serbia, Hungary, and Ukraine also maintain riverine units, but none possess capabilities comparable to those of their Romanian counterparts. The main striking force of the Danube Flotilla are the three Mihail Kogălniceanu class river monitors. These vessels are heavily armed and armored vessels that can be used on the river, as well as in shallow coastal waters.
Each ship is equipped with two A-407 100 mm cannons, installed in tank turrets. The turrets are not standard T-55 or TR-85 tank turrets, but of a fully welded design. These types of turret designs are used only by the heavy ships of the Danube Flotilla, monitors and armored gunboats. Turret gunnery includes a Romanian improved version of the Soviet D-10T tank gun, which uses the same ammunition and is manually loaded and fired.
For long range fires, each monitor is equipped with two GRAD 122 mm rocket launchers which are housed internally in armored recesses. Each launcher can launch forty 122 mm rockets at a maximum range of 20 km. Recently the monitors and the armored gunboats have been equipped with 122 mm rockets that can reach up to 35-40 kilometers (km) . The 122 mm rockets are the main fire support weapons of the monitors and armored gunboats. Although in theory the 100 mm cannons can fire rounds up to 22 kilometers, their range is limited due to the elevation of the tank turret.
For air defense, each monitor is equipped with two twin A-436 30 mm mounts. These are Romanian-made 30 mm automatic guns derived from the Soviet AK-230a system. These are revolver type cannons with four chambers that can fire 100, 250 or 500 rounds per minute per barrel. Each mounting has an available ammunition supply of 30 rounds per barrel that must be manually replaced. As with the tank cannons, both air defense mountings are manned and there is no dedicated air defense fire control radar. Aiming is done via optical devices installed on the mounting and the weapons can engage both aircraft and surface targets. The automatic cannons are installed on top of the superstructure behind the armored citadel.
For close in air defense and engaging small targets on land and river, two MR-4, four barreled 14.5 mm heavy machine guns are used. These mounts are manned and are aimed optically. There are no provisions for night vision devices. In addition, a number of MANPADs are carried on board by Romania’s riverine forces, that can be launched from the deck of the ship. No special mountings or installations for the MANPADs exist and are launched manually by one or more sailors aboard.
Every vessel is equipped with radio and navigation radars. Since 2018, these ships have been put through a mid-life update which changed their propulsion systems, electrical systems and added a FLIR. At present the last of the monitors, Lascăr Catargiu (47) should soon be modernized. Unfortunately, no major weapons refit has been undertaken or scheduled for Romania’s riverine forces and its flotilla continues to be equipped with Warsaw Pact standard weaponry.
In the current threat environment of the Black Sea region, Romania’s riverine forces remain highly vulnerable to air attacks from helicopters armed with long-range anti-tank missiles, strike fighters, loitering munitions, and Uncrewed Surface Vehicles (USVs). Should a weapons refit be carried out in the near future, the air-defense artillery should be replaced with modern 30 mm or 35 mm air defense systems. However, there are plans to replace the Soviet and Romanian made MANPADs with French Mistral missiles acquired through the EU’s EDIRPA program.
The other major vessels used by the Danube Flotilla are its armored gunboats. Five of these were built in the late 1980s and early 1990s. In many respects, they are smaller variants of the monitors. Both the monitors and the armored gunboats are based in Brăila (see map above).[1] The 2018 modernization program began with the armored gunboats which have been upgraded with Korean diesel engines, a new electrical system, communications and command systems and FLIR to permit night-time operations. According to Vice-Admiral Panait, commander of the Romanian Naval Forces, the Danube Flotilla will receive Israeli-made Spike LR anti-tank missiles. However, it is unknown if the anti-tank missiles are going to be installed on ships or whether they will used only by Romanian Marines attached to the flotilla.
The third type of vessel used by the Danube Flotilla is a dozen patrol boats, equipped for river patrol duties and mine warfare. These are the oldest combatants of the Flotilla, built in the 1970s and 1980s. The patrol boats are light combatants, with an aluminum hull and are equipped with automatic cannons and heavy machine guns. Each boat is equipped with two 30 mm guns and a MR-4 heavy machine gun mount. Six of these vessels are equipped with minesweeping gear and all of them can deploy six naval mines. Romania’s patrol boat fleet is organized into two squadrons, one based in Brăila and the other in Tulcea.
Naval Infantry
The 307th Marine Infantry Regiment Heracleea is the unit tasked with fighting on the river and in the Danube Delta. The regiment was created in 2018 by increasing the size of the 307th Marine Infantry Battalion. The unit is composed of a command element, a marine infantry battalion, a support battalion and a logistic’s company. The support battalion is made up of an ISR company, an artillery battery and a headquarters company. The battalion can be deployed from the Danube Flotilla in small detachments, as well as from the monitors, armored gunboats, and patrol boats. The monitors and armored gunboats are specifically designed to facilitate troop landings by deliberately grounding on riverbanks. The regiment can also deploy from landing barges or rubber assault boats for covert missions.
To enhance their operational mobility in the Danube Delta each battalion is also equipped with light 4x4 armored amphibious vehicles (ABC-79). Recently, Romania has announced its intent to acquire from US stocks 44 AAV-7 tracked amphibious vehicles and refurbish them for $ 210 million. The addition of the AAV-7 will greatly increase Romanian marine mobility on the canals of the Danube Delta, as tracked vehicles are far more suitable for muddy conditions. The regiment has also received Spike LR fiber optic guided anti-tank missiles which can be used against armored fighting vehicles and enemy warships.
The Russian-Ukraine War and Riverine Warfare
A relatively unreported aspect of the naval war between Russia and Ukraine is the struggle to control the Dnipro (Dnieper), a river that almost divides the country in two as it flows from north to south toward the Black Sea.
Along the Black Sea littoral, rivers become effective natural barriers that are often used in support of defensive operations. Forced river crossings are a highly complex military operation, which require adequate planning, preparation and effective air cover. Control of a long navigable river is therefore critical for logistics and control of adjacent territories. This is especially true in southern Ukraine where Russian and Ukrainian forces have been fighting for control of the Dnipro Delta since the onset of the war. Small unit raids using assault boats, FPV drones and USVs have been employed by both sides in order to gain control of certain sections of the river or to establish bridgeheads.
When it comes to the Danube, Russia has not limited itself to strikes on Ukrainian infrastructure. The Ukrainian intelligence vessel the Simferopol was struck by a Russian USV and sunk, in the Danube Delta on August 28, 2025, in what was the first successful employment of USVs by Russian forces in the war.
What was remarkable about the attack was that Russian force used a USV to infiltrate one of the Ukrainian canals from the Black Sea and struck the Ukrainian vessel while at anchor. The strike demonstrated that the respective mouths of the Danube can be easily infiltrated not only by Russian USVs but also by Russian naval special forces. Based in neighboring Crimea as part of the Russian Black Sea Fleet, Russian naval Spetsnaz forces likely coordinated the August attack and can be easily deployed from their naval base at Sevastopol to raid or carry out reconnaissance missions in the Danube Delta. These missions can be carried out using boats, submarines and even small submersibles.
Future Outlook
While on paper Romania’s Danube Flotilla appears quite formidable, it suffers from a number of significant drawbacks in meeting future threats. Only small boats for hydrographic and diver support have been acquired over the past 20 years to equip the unit. The flotilla’s ships are old and mostly consist of Warsaw Pact era vessels. Due to their age they can operate effectively only in conditions of NATO and Romanian air supremacy. The newest are the three river monitors, built in the 1990s, while the oldest are the patrol boats built in the late 1970s and early 1980s.
One of the key drawbacks to these vessels are the lack of NATO caliber weaponry and the absence of modern firepower. It is unlikely for the monitors and armored gunboats to bring down an aircraft using manually operated mounts, without night vision devices or effective stabilization. Flotilla warships lack modern air defense and are devoid of weapons stations and modern sensors, particularly against loitering munitions or First-Person View (FPV) drones. None of the ships in Romania’s riverine fleet are equipped with effective electronic countermeasures suites to deal with drones, loitering munitions, and missiles, not to mention fiber-optic–guided drones.
The development of sea and riverine based Uncrewed Surface Vehicles (USVs) during the Russian-Ukrainian war has created a new set of threats to the Danube Flotilla, exposing vulnerabilities that require attention and action. The August 28 Russian USV attack - inside the Danube - on the Ukrainian intelligence ship Simferopol is a major lessons learned from the conflict. Recent assessments of the attack have underscored the vessels lack of anti-USV weaponry and the lack of proper defense preparations employed prior to the attack, such as setting up protective barriers around the ship. These measures were not put in place by the crew of the Ukrainian vessel prior to its sinking (for an in-depth assessment of this attack please watch the recent Saratoga discussion of the event 👉 here).
In the medium term, monitors and armored gunboats can still serve effectively as mobile weapons platforms in support of ground forces and riverine operations, though they require significant upgrades, particularly in air defense. Patrol boats should not be overhauled or upgraded but replaced with newer, more capable vessels. Additionally, new ships capable of deploying USVs, UAVs, and loitering munitions should be built and acquired.
For the long term, a new class of monitors and armored gunboats should be developed, incorporating the naval lessons of the Russia–Ukraine war—such as enhanced air defense, integrated electronic warfare systems, and the capability to employ guided weapons, including long-range anti-tank missiles, precision artillery shells, and guided rockets.
Footnotes:
[1]Each vessel is armed with only one 100 mm cannon but carry two GRAD 122 mm rocket launchers with 40 launch tubes each, known in Romanian service as APRA. For air defense there is only one 30 mm mount installed aft and two MR-4 14.5 mm mounts forward of the citadel, behind the main gun. Two APC turrets with 14.5 mm heavy machine guns and 7.62 general purpose machine are installed parallel with the main gun turret, but on a lower level.
About the Author:
George Vișan is an expert on Romania and Black Sea Security and works as an expert on issues of peace and war for the Romanian Diplomatic Institute. He holds both undergraduate and postgraduate degrees in Political Science and International Relations from the University of Bucharest, and has published extensively on Romanian security and defense policy. From February 2022 to February 2024, he served as an advisor to the State Secretary for Strategic Affairs at the Ministry of Foreign Affairs (MAE). His opinions and research in this article are his own and do not reflect the official positions of the Romanian Diplomatic Institute nor the Ministry of Foreign Affairs of Romania.
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