Three drone incidents in 36 hours last week highlighted the growing security challenge facing Nato's Black Sea flank, culminating in Romania scrambling an F-16 to destroy an explosive-laden naval drone near the country's biggest new offshore gas project.

European officials have warned that repeated drone incursions into Nato territory are increasingly difficult to dismiss as accidental spillover from the war in Ukraine.

The first incident occurred at 02.23 on August 20, when Romanian radar detected an aircraft north of Tulcea county, as detailed by Euronews. It entered Romanian airspace at 0321, about 13 km east of Galati, and crashed three minutes later, about 4 km northeast of the village of Grindu. Two Spanish F-18s and a Romanian IAR-330 SOCAT helicopter were scrambled, according to Euronews.

Three hours later, at 06.28, the Romanian coastguard spotted a naval drone carrying explosives a few hundred metres from the Neptun Alpha gas platform, around 80 nautical miles east of Constanta. One of two Romanian F-16s destroyed it.

Overnight into August 21, Russian drones damaged the Tabaky border crossing between Ukraine and Moldova in Ukraine's Odesa region, forcing traffic to be suspended.

"An escalating campaign of threats is underway, unsettling our citizens and seeking to divide our Union," European Commission President Ursula von der Leyen wrote on X on August 21. "This is hybrid warfare."

For much of the war, drones entering the airspace of Romania, Moldova, Bulgaria and the Baltic states have been described as strays - weapons knocked off course by electronic warfare or otherwise unintentionally crossing borders.

That explanation has become harder to sustain as incidents have multiplied. A purpose-built naval drone carrying explosives and found beside critical offshore energy infrastructure is difficult to characterise as an accidental incursion.

From strays to a pattern

The number and frequency of incidents have increased sharply over the past year. In September 2025 between 19 and 21 Russian drones entered Polish airspace and flew halfway across the country; Warsaw triggered Nato's Article 4 for the first time in the alliance's history.

On November 25, drones crossed into both Romania and Moldova, one of them landing on the roof of a house in Cuhurestii de Jos.

By April 2026, Moldova was logging three airspace violations in a single week. On April 25 a Geran-2 carrying explosives flew 15 km at low altitude over Romanian territory and crashed on the northern edge of Galati, damaging an outbuilding and a power pole; debris from two more drones turned up in Tulcea county over the following day, and Bucharest summoned the Russian ambassador.

On the night of June 7-8 a drone with an explosive payload detonated at Lopatna in Moldova, 50 km from Chisinau, while on the same night a French jet shot one down over Latvia. Between July 24 and 26 Romanian F-16s downed three drones in three days, and on July 27 Romania expelled a Russian diplomat and recalled its ambassador from Moscow.

Then on August 8 a drone crossed roughly 100 metres into Bulgaria from Romania and exploded near the town of General Toshevo. Romania's radar had not seen it cross. Sofia ordered more counter-drone systems the following week.

Four years of war have produced a Russian drone force that no longer resembles the one Nato planned against. Moscow is out-producing Ukraine across its whole missile and drone arsenal, and the newest Geran-4 and Geran-5 classes are jet-powered, fly close to 1,000 km with a 90 kg warhead and are far harder to intercept than the propeller-driven Shaheds.

The Telegraph reported on August 16, from satellite imagery and leaked documents, that Russia has built ten launch-pad bases along the Ukrainian and Belarusian borders carrying at least 59 rails, roughly 20 of them lengthened for the bigger aircraft.

That infrastructure potentially puts Poland, Romania, Turkey and the Baltic states within the arc of Russian drone operations.

The problem of attribution

Not every drone entering Nato airspace is Russian. Latvia's armed forces said on August 20 that debris from a drone shot down over Balvi municipality on August 14 was of Ukrainian origin, Brussels Signal reported. Officials declined to identify its model, saying that could reveal information affecting Ukraine's defensive operations. Latvian officials believe it entered from Belarus.

"The risks of drones flying in exist," Defence Minister Raivis Melnis told Latvian Television. "Ukraine, in defending itself, is continuing strikes on Russian territory with drones as well, while Russia is carrying out countermeasures."

Russian electronic warfare can disrupt Ukrainian drones and send them off course, creating an awkward situation for Nato governments that must decide whether to treat an incursion as an attack.

Latvia also identified a Ukrainian-origin drone in March. Neither incident caused casualties and both were shot down over Nato territory.

Warsaw's security committee reviewed the risk of a Russian false-flag operation using captured Ukrainian drones in July, with Defence Minister Wladyslaw Kosiniak-Kamysz warning they could be turned against the Baltic states, Finland, Romania or Poland itself. Neither government has published evidence that such an operation has taken place.

After a Ukrainian drone was found deep inside the port of Constanta, Bucharest and Kyiv used a direct communication channel within minutes. Kyiv confirmed that the naval drone found near the gas platform was not Ukrainian.

A five-kilometre bubble

This month, Bulgaria ordered counter-drone systems from US company Axon, receiving the first two of four and considering up to 10. The mobile platforms combine radar, sensors, cameras and jammers, but have an effective range of only about three to five kilometres.

"Two anti-drone systems are useless," said Todor Ivandzhikov, chairman of the Association of the Bulgarian Aviation Industry, according to Bloomberg TV Bulgaria. "A circle of 3-5 km will not save Bulgaria."

The problem is therefore not simply the number of systems but the lack of a layered network combining low-altitude radar, drone detection, electronic warfare and command centres.

Latvia faces a similar problem. Melnis has acknowledged that the country lacks sufficient counter-drone systems and radar along its eastern border. Latvian equipment is intended to cover the frontier with Russia and Belarus by the end of September, although the timetable is under review.

Latvia has no combat aircraft of its own and relies on allied deployments. Italian Eurofighters are currently based in Lithuania as part of Nato's Baltic air policing mission.

The economics are also unfavourable. Poland reportedly spent about $1.2 billion countering drones costing $10,000-$20,000 each, against a Russian production capacity estimated at roughly 2.5 million drones a year.

Using an F-16 and an expensive missile to destroy a cheap drone is not a sustainable long-term solution.

Von der Leyen used the Neptun Deep incident to push the EU's Eastern Flank Watch, the counterpart to the European Drone Wall she first called for in her 2025 State of the Union address. The two projects are meant to give the Union a multi-layered network able to detect, track and neutralise hostile drones along its eastern border. They were due to launch in the first quarter of 2026, reach initial operating capability by the end of this year and be fully functional by the end of 2027.

Nato has also established Eastern Sentry following the Polish incursions of September 2025 and agreed to broaden Baltic Air Policing into an air-defence mission. Romania has proposed an EU Centre for Maritime Security in the Black Sea, with one headquarters in Constanta.