War in the Black Sea is Testing NATO's Red Lines

Attacks on commercial ships near Romania and Bulgaria are testing NATO’s ability to protect its Black Sea flank, with further strikes following an alliance pledge to strengthen surveillance and defenses.

After seven cargo ships were hit last month, NATO announced plans to send maritime patrol aircraft, radar systems and drones to the region.

Another vessel was struck outside Romanian waters on October 23, three days after the announcement.

Last week, naval drones sank a Greek container ship in Bulgaria’s exclusive economic zone, extending a campaign that analysts say is probing the alliance’s willingness to respond.

Of the nine ships struck, one was inside Romanian territorial waters. The remaining eight were in the exclusive economic zones of Romania or Bulgaria.

Attribution and Deterrence

Military analysts consider Russia responsible. Shipping security company Ambrey said a drone visible in footage of the latest attack resembled a Russian model.

Romania has accused Moscow of systematically attacking civilian shipping but says forensic evidence is needed to attribute individual strikes.

Bulgaria has avoided naming Russia, while saying some attacks appear to serve its interests.

Moscow denies directing drones against Ukraine’s neighbors and accuses European governments of escalating the conflict through military assistance to Kyiv.

Iulia Joja, who leads the Middle East Institute’s Black Sea program, told Reuters that Russia was exploiting Western reluctance to escalate.

“This is about testing these red lines, with full awareness that we will do everything possible to take the most minimal measures,” she said.

A NATO official described Russian efforts to deter support for Ukraine as a serious security threat and reiterated the alliance’s commitment to defend its members.

Gaps in Protection

Bucharest wants additional radar systems and surface-to-air interceptors.

Joja said shortages of inexpensive interception weapons, compounded by the war in Iran, were a central weakness.

NATO says it has committed more than $40 billion to counter-drone capabilities over five years.

However, Joja said Romania had not received reinforcement comparable to what Poland and the Baltic states received, despite requesting it.

The pressure comes as Washington reviews its European military presence while prioritizing China. The U.S. removed 1,000 troops from Romania last year.

“It’s a moment in the transatlantic relationship that Putin likely wants to use,” a senior Romanian official said.

Romania’s exposure extends beyond shipping. A naval drone approached its offshore Neptun Deep gas project in August.

The development is expected to make Romania the EU’s largest gas producer next year.

Export Routes Under Attack

Several targeted ships were using, or waiting near, the Romanian canal route that has become increasingly important to Ukrainian exports.

Ukraine halted operations at its Black Sea ports in late July following Russian attacks, redirecting cargo through Danube ports and Romania’s Sulina Canal.

Its September grain exports through ports nevertheless fell to 0.81 million metric tons from 2.1 million a year earlier.

Russian grain shipments through the Black Sea and Sea of Azov dropped to 0.3 million metric tons from 4.74 million.

Ambrey recorded 317 merchant and other vessels hit by Russia and Ukraine across the two seas between May and October, against 74 during the preceding six months.

Former Ukrainian naval officer Andriy Ryzhenko said restricting Ukraine’s exports remained Russia’s principal objective, with testing NATO a secondary aim.

Maritime Ceasefire Efforts

The latest sinking coincided with talks in Sofia between defense leaders from Romania, Bulgaria and Türkiye.

Türkiye warned both combatants against further attacks and is awaiting their responses to a limited maritime ceasefire proposal.

Moscow has rejected a narrow truce, arguing it would give Kyiv breathing space.

Egypt and India have also sought a shipping ceasefire. U.S. Secretary of State Marco Rubio said Saturday that international interest in a limited agreement was increasing.