European Commission President Ursula von der Leyen was flying into Bulgaria when her planes GPS system was jammed in a suspected Russian operation, forcing pilots to rely on backup navigation and old-school paper maps to land safely.

This was only the latest episode in a growing and worrying tactic in modern conflict zones: GPS jamming.

As von der Leyens plane approached Plovdiv Airport, the GPS signals guiding the plane suddenly vanished. Pilots found themselves flying "blind" in terms of satellite navigation for almost an hour. Despite the disruption, they switched quickly to backup systems and landed safely without incident.

According to Bulgarian officials, GPS jamming -- Moscow denied any role in von der Leyen's flight -- and spoofing have become so frequent that individual cases like von der Leyens are no longer specially investigated.

But former Defense Minister Todor Tagarev disagrees.

If there was any jamming, it couldnt have come from outside the country, Tagarev told RFE/RLs Bulgarian Service.

He added that in such circumstances, the security services need to figure out what happened.

GPS jamming and spoofing cases are on the rise, according to aviation analysts, especially in aviation and maritime sectors, particularly around conflict zones such as Ukraine and the Black Sea and Eastern Europe.

In March, the United Nations agencies for telecommunications, aviation and maritime shipping called for "urgent protection" of the radio navigation satellite service (RNSS) that supports accurate global navigation and timekeeping.

How Are Signals Jammed?

GPS signals can be lost through natural phenomena such as solar storms or as a result of equipment failures. But these cases are usually brief and planned for in commercial aviation, minimizing the risk to commercial flights.

GPS jamming involves broadcasting radio signals on the same frequencies as GPS satellites to overwhelm and block legitimate navigation signals.

The principle works like this: GPS satellites broadcast weak radio signals at specific frequencies. A receiver picks up signals from at least four satellites and uses the timing information to calculate coordinates.

So, what does jamming do? Put simply, it transmits a stronger signal on the same or nearby frequencies, effectively drowning out the signals from the satellites.

The result is that the receiver cant connect to the satellites and loses its signal. In some cases, if instead of jamming a system is spoofed, the receiver may display false coordinates.

Though jamming devices can be inexpensive and technically simple, they usually only work over short distances -- a few hundred meters for small jammers or several kilometers for more powerful military-grade systems.

The jammers involved in von der Leyens incident werent located thousands of kilometers away in Russia but were close to European airspace. In fact, experts who spoke to RFE/RL said the source of the interference signal was located near the airport.

GPS spoofing is slightly different: This is a method of placing an aircraft somewhere where it isn't. This is done through creating a copy of a plane's signal and then transmitting it to make it look like an aircraft is somewhere else or to change the time that it appears to be operating.

Spoofing can only be done deliberately through special devices that decode and replicate a plane's GPS transmitter.

If It's Easy, Why Isn't It More Common?

Jamming is illegal in most countries and easy to detect and locate, so perpetrators risk being caught.

Additionally, because GPS is used widely -- from cars to ships to smartphones -- jamming causes widespread disruption beyond aviation, making it a risky choice outside military or conflict contexts.

However, military jamming and spoofing are increasingly common in conflict zones. The incidents have increased since Russias full-scale invasion of Ukraine in 2022 and have only become more frequent since.

Jamming can sometimes be used for defensive purposes, but experts argue that Russia is increasingly targeting European countries this way to sow confusion and fear.

After the incident with von der Leyen, the European Commission directly blamed Russia and announced sanctions against several companies linked to GPS signal disruptions. It also said it is developing an aviation-specific plan to prevent future jamming.

Elitsa Simeonova of RFE/RLs Bulgarian Service contributed to this report.