Belgium’s defense minister said a series of unidentified drones flying over a military base that is reported to house U.S. nuclear weapons could be part of a spying operation.

Theo Francken wrote on his X account that multiple drones were spotted above the Kleine-Brogel Air Base in northern Belgium over the weekend.

“A drone jammer was used, but without success… A helicopter and police vehicles pursued the drone, but lost it after several kilometers,” he said.

“Thanks to the guard for their attention and follow-up. Thanks to the police services. We continue to strengthen our vigilance in order to apprehend the pilots.”

NATO COUNTRY REPORTS DRONES OVER LARGEST MILITARY BASE AFTER AIRPORT ATTACK, MULLS RESPONSE

Belgian Minister of Defense Theo Francken addresses the media during the official F-35 opening ceremony at Florennes Air Base on October 13, 2025, in Brussels, Belgium. (Thierry Monasse/Getty Images)

Francken told RTBF, Belgium’s French-language public broadcaster, the situation was “very concerning” and “worrying.”

The defense minister added that the incidents were under investigation but suggested they could have been part of a spying operation.

“They [the drones] come to spy, to see where the F-16s are, where the munitions are, and other highly strategic items,” Francken told RTBF. “It’s not a drone that just happened to cross the military base. It was there for a long time, so it was definitely for spying.”

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Kleine-Brogel is integral to NATO’s nuclear deterrence posture in Europe and houses F-16 fighter jets, according to its website. The air base said on its website that the jets will be replaced in a few years by the F-35A, the U.S. Air Force’s latest fifth-generation fighter.

Nuclear watchdogs have reported the base as home to U.S. nuclear bombs under NATO weapons sharing agreements.

A Belgian F-16 jet takes part in NATO’s “Steadfast Noon” nuclear deterrence drill at Kleine-Brogel Air Base in Belgium on October 18, 2022. (Kenzo Tribouillard/AFP via Getty Images)

In a series of airspace incursions in September, Russian drones entered Poland and three MiG-31 fighter jets crossed into Estonia, prompting NATO aircraft to intercept and escort them out.

Belgium’s defense minister said he couldn’t confirm Russia was behind the drones over Kleine-Brogel but noted the Kremlin’s motives were clear and accused Moscow of waging a “hybrid war” across Europe.

President Donald Trump told reporters in September on the sidelines of the United Nations General Assembly that NATO countries should shoot down Russian aircraft that violate their airspace.

A “No Drone Zone” sign is displayed in central Moscow on January 11, 2024, prohibiting the use of unmanned aerial vehicles in the area. (Natalia Kolesnikova/AFP via Getty Images)

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NATO Secretary General Mark Rutte also warned Moscow after a series of drone incursions that the 32-member alliance is prepared to defend every inch of NATO territory.

“We are a defensive Alliance, yes, but we are not naive, so we see what is happening and whether it is intentional or not – if it is not intentional, then it is blatantly incompetence,” he said. “And of course, even if it is incompetence, we still have to defend ourselves.”