On 14 August 2024, a suspected sabotage at the Bundeswehr air base in Köln-Wahn and suspicious activities at NATO's Geilenkirchen base in North Rhine-Westphalia, Germany, led to investigations due to abnormal water quality and fence breaches.

On the night before 14 August 2024, unusual water quality readings were detected during routine testing at the Bundeswehr air base in Köln-Wahn, Germany. A breach was discovered in a perimeter fence large enough for a person to pass through, prompting an immediate lockdown and investigation including police, state protection, Military Counterintelligence Service (MAD), and military police. Although no intruders were found, video footage is under review. Separately, suspicious observations led to a raised security status at the nearby NATO Air Base in Geilenkirchen, where a person was found near the fence but not detained. Water testing at Geilenkirchen showed no irregularities. Bundeswehr and NATO officials treat the incidents seriously, with Minister Boris Pistorius calling for heightened vigilance. Parliamentary defense officials suspect the sabotage attempt may be a demonstration of hostile actor capabilities, with references to Russian motives amid ongoing conflict dynamics. The Köln-Wahn base is a key logistics and training hub supporting Ukraine. Investigations continue, with no confirmed illnesses or further disruptions reported.