The GPS of a plane carrying the president of the European Commission, Ursula von der Leyen, encountered suspected Russian interference while trying to land in Bulgaria, a spokesperson for the Commission told TIME.

“We have received information from Bulgarian authorities that they suspect this blatant interference was carried out by Russia. We are well aware that threats and intimidation are a regular component of Russia’s hostile actions,” said European Commission Deputy Chief Spokesperson Arianna Podestà in an emailed statement, reiterating that the plane landed safely on Sunday despite the GPS jamming.

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Per Podestà, the event will only serve to “further reinforce” the European Commission’s “unshakable commitment to ramp up [its] defence capabilities and support for Ukraine.”

A source familiar with the matter told TIME the pilots used paper maps to successfully land the plane.

TIME has reached out to Bulgarian Authorities and the Russian Foreign Ministry regarding the allegations.

A strong ally of Ukrainian President Volodymyr Zelensky, von der Leyen has frequently condemned Russia’s actions against Ukraine following its invasion of the country in 2022.

Last week, she lambasted the Russian strikes that hit the E.U. delegation in Kyiv for the first time, along with the British Council building. “Russia must stop its indiscriminatory attacks on civilian infrastructure immediately and join negotiations for a just and lasting peace,” she urged.

Read More: European Leaders Condemn Putin’s ‘Bloodshed’ After Russia Strikes Kyiv’s E.U. Mission and British Council Buildings

On Sunday, von der Leyen visited an ammunition factory in the Bulgarian town of Sopot, where she said that shells are manufactured for both E.U. and Ukrainian stockpiles and praised the site for benefiting “Europe’s security as a whole.”

Continuing her tour of frontline member states on Monday, von der Leyen visited Lithuania, which borders Russia, and announced an economic roadmap for the next five years is due to be outlined in October to address defence investment regarding the war in Ukraine and Russian threats towards other neighbouring countries.

“You live under geopolitical and economic pressure, as well as constant military and hybrid threats,” said von der Leyen in a joint press conference with Lithuanian President Gitanas Nausėda.

In July, the European Commission announced sanctions against Russian individuals and entities accused of these “hybrid threats,” including one Russian company and two individuals in relation to signal jamming from Kaliningrad, a Russian exclave.

“GNSS signal disruptions in several European countries have been linked to electronic warfare activities from Kaliningrad, including jamming and spoofing of GNSS signals, primarily affecting the Baltic States, and disrupting civil aviation,” read the press release.

Read More: How Putin Brushed Off Trump’s Latest Push for Peace in Ukraine

The latest allegations of Russian interference in GPS systems comes almost three weeks after U.S. President Donald Trump met with Russian President Vladimir Putin in Alaska for a “high-stakes” summit.

The meeting served as the first in-person encounter between the Presidents since 2019, and was intended to foster discussions about a path toward a potential cease-fire. But it ended earlier than expected and, notably, without a deal being reached.

Trump has since met with Zelensky and key European leaders at the White House to discuss possible steps forward, during which he ruled out sending U.S. troops to Ukraine as part of security guarantees.