NATO takes the issue "very seriously" and is "working day and night to counter this, to prevent it, and to make sure that they will not do it again," Secretary General Mark Rutte said.

A plane carrying the European Commission President Ursula von der Leyen was targeted by GPS navigation jamming while trying to land in Bulgaria on Sunday, a spokesperson for the commission told CNN.

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.