The NATO air base in Germany was reportedly under threat of Russian drone attacks.
According to German media reports, an alert was raised last week of a possible Russian drone attack.
The security level was temporarily raised on the 22nd of August after receiving a tip-off from foreign intelligence over signs of “Russian sabotage”.
The Geilenkirchen air base houses the Western alliance's fleet of AWACS surveillance planes.
About 1,600 people work at the airfield, which stations special aircraft to monitor airspace in NATO’s eastern theatre.
The base's radar is capable of locating and identifying other aircraft at a range of more than 400 kilometres.
The incident comes amid warnings from Russia over Ukraine's Kursk incursion.
President Vladimir Putin has been blaming US and its allies for Ukraine’s renewed assault on Russian territories. As a result, the Western forces have been on alert.
Days before the latest incident, the same NATO air base was temporarily closed over fears that its water supply system had been intentionally contaminated.
German newspaper Bild reported that no abnormalities were found after an inspection.
The tabloid also reported last week that Germany was investigating suspected Russian surveillance drone flights flying over key nuclear infrastructure in Brunsbüttel, a city in the north of the country near the coast of the North Sea.