SOFIA, Bulgaria (AP) — A plane carrying European Commission President Ursula von der Leyen was hit by GPS jamming over Bulgaria in a suspected Russian operation, a spokesman said Monday.

The plane landed safely at Plovdiv airport in central Bulgaria and von der Leyen will continue her planned tour of the European Union’s eastern frontline nations, said commission spokesperson Arianna Podest.

“We can indeed confirm that there was GPS jamming,” said Podestà. “We have received information from the Bulgarian authority that they suspect that this was due to blatant interference by Russia.”

The incident with von der Leyen’s plane is the latest in a series involving suspected Russian electronic interference with GPS satellite navigation. For months, countries bordering Russia — including Finland, Latvia, Lithuania and Estonia — have warned of increased electronic activity interfering with flights, ships and drones. Russian authorities did not immediately reply to requests for comment.

Von der Leyen, a fierce critic of Russian President Vladimir Putin and Moscow’s war in Ukraine, is on a four-day tour of much of the EU’s eastern flank, with stops in Lithuania, Finland, Estonia, Latvia, Poland, Romania, and Bulgaria.

“This incident actually underlines the urgency of the mission that the president is carrying out in the front-line member states,” Podestà said.

She said that von der Leyen has seen “firsthand the everyday challenges of threats coming from Russia and its proxies.”

“And, of course, the EU will continue to invest into defense spending and in Europe’s readiness even more after this incident,” she said.Bulgaria issued a statement saying that “the satellite signal used for the aircraft’s GPS navigation was disrupted” during von der Leyen’s flight.

She was traveling from Warsaw, Poland, to Plovdiv, Bulgaria’s second-largest city, on a private jet chartered by the European Commission. “As the aircraft approached Plovdiv Airport, the GPS signal was lost,” the statement said. It said that Bulgaria’s Civil Aviation Authority instructed the pilots to use backup navigation aids to land the plane.