BRUSSELS, Belgium — A plane carrying EU chief Ursula von der Leyen was hit by GPS jamming as it readied to land in Bulgaria on Sunday, Brussels said Monday, asserting that Russia was thought to be behind the incident.

“We can indeed confirm that there was GPS jamming, but the plane landed safely in Bulgaria. We have received information from the Bulgarian authorities that they suspect that this was due to blatant interference by Russia,” an EU spokesperson said.

The Russian government did not immediately reply to a request for comment.

The EU gave no further details, but the spokesperson said the incident would reinforce the bloc’s “unshakable commitment to ramp up defense capabilities and support for Ukraine” against Russia’s three-and-a-half-year-old invasion.

The aircraft landed safely at Plovdiv International Airport, in the south of the country, without having to change route.

Commission president Von der Leyen, 66, was in Bulgaria as part of a seven-country tour of “frontline” European Union states which, sitting on the 27-nation bloc’s eastern flank, are more exposed to Russian hybrid threats.

The region has experienced “a lot of such jamming and spoofing activities,” the commission said, adding it has sanctioned several companies believed to be involved.

The Bulgarian government confirmed the incident.

“During the flight carrying European Commission president Ursula von der Leyen to Plovdiv, the satellite signal transmitting information to the plane’s GPS navigation system was neutralised,” a government statement said.

“To ensure the flight’s safety, air control services immediately offered an alternative landing method using terrestrial navigation tools,” it said.

The Financial Times newspaper, which first reported the incident, said the plane was forced to land using paper maps.