BERLIN

The threat level at a major air base in Germany has been lowered again, NATO officials said on Friday.

Security at the Geilenkirchen air base, where military alliance's AWACS surveillance aircraft are stationed, was raised on Thursday afternoon due to an unspecified threat.

"The security level at NATO Air Base Geilenkirchen has returned to Bravo+. The temporary rise to Charlie was a precautionary measure to minimise potential risk to our organization and personnel,” the air base said in a statement.

Security alert “Charlie” applies at NATO bases when an incident occurs or intelligence is received indicating some form of terrorist action, or targeting against personnel or facilities is likely.

On Thursday afternoon, after receiving intelligence on a potential threat, all non-mission essential staff at the air base were sent home as a precautionary measure.

NATO officials said on Friday afternoon that all scheduled operations were now proceeding as planned.

More than a dozen AWACS airplanes are stationed at the Geilenkirchen base, which are tasked with air and sea surveillance, and can be used as a flying command center in combat aircraft operations.

In recent years, NATO AWACS aircraft conducted hundreds of flights over Eastern Europe to monitor Russian military activity near the alliance’s borders.