The navigation system of a plane carrying Ursula von der Leyen was disrupted due to suspected Russian interference, the European Commission has said.
A spokesperson said the GPS jamming happened while the Commission president was about to arrive in southern Bulgaria on Sunday, but she still landed safely.
They added: We have received information from the Bulgarian authorities that they suspect that this was due to blatant interference by Russia.
The Financial Times, citing unnamed officials, reported that von der Leyen's plane had to land at Plovdiv Airport with the pilots using paper maps.
The European Commission said threats and intimidation are a regular component of Russia's hostile actions and that the incident would reinforce its commitment to ramp up our defence capabilities and support for Ukraine.
The EU will deploy additional satellites into low Earth orbit with the aim of bolstering its ability to detect GPS interference, the bloc's Defence Commissioner Andrius Kubilius said following the incident.
The Bulgarian government confirmed that, during the flight, the satellite signal transmitting information to the plane's GPS navigation system was neutralised.
The statement continued: To ensure the flight's safety, air control services immediately offered an alternative landing method using terrestrial navigation tools.
Kremlin spokesperson Dmitry Peskov told the FT that its information was incorrect.
The Bulgarian Air Traffic Services Authority said there had been a noticeable increase in GPS incidents, including jamming, since February 2022 - when Russia launched its full-scale invasion of Ukraine.
Tens of thousands of incidents of jamming have been reported by airlines operating around the Baltic coast in the last few years. The three Baltic nations - Latvia, Lithuania and Estonia - are bookended by Russian territory.
In March 2024, an RAF plane carrying the UK's then-Defence Secretary Grant Schapps reported a spoofing incident - in which legitimate signals are replaced with fake ones, indicating a false location.
The plane, which had been flying near the Russian exclave of Kaliningrad, which sits between Poland and Lithuania, was able to continue its journey safely.
The issue has become so prevalent that the European Union Aviation Safety Agency (EASA) and the International Air Transport Association (IATA) convened a special conference in 2024 to discuss spoofing incidents - warning they could pose significant challenges to aviation safety.
Several eastern European foreign ministers have also sounded the alarm, saying that if GPS signals for aviation continue to be disrupted, an air disaster could not be ruled out.
But there are some who dispute the seriousness of GPS jamming. The UK's Civil Aviation Authority (CAA) told the BBC that aircrafts' complex navigation systems... do not solely rely on GPS, as such, any interference does not affect the direct navigation of aircraft.
Moscow regularly denies accusations of interference or attacks on commercial aviation, and no proven link has yet been established between Russia and the rise in GPS jamming.
While planes can rely on other forms of navigation than GPS, jamming it mid-flight can increase the risk of collisions – either with other planes or by causing the pilot to unintentionally fly into the ground, water or other obstacles.
Keir Giles, a senior consulting fellow at Chatham House's Russia and Eurasia Programme, told the BBC such interference had indeed become a constant feature of flying near Russia, disrupting time and positioning services that had previously been taken for granted.
Von der Leyen was visiting Bulgaria as part of a tour of eastern EU states to discuss defence readiness, where she had seen first hand the every day threats from Russia and its proxies.
