Copenhagen Airport suspended flights on September 22 when the objects were seen in its airspace.
In the days that followed, the Danish air force's main fighter jet base and other airports also suspended operations after similar incidents.
"We cannot confirm that there has been drone activity in and around the airport. At the same time ... we cannot rule out the possibility that there has been drone activity," Chief Police Inspector Soren Thomassen told reporters.
No suspects had been identified and the investigation was closed, he added.
The incidents last year were seen as being part of a growing pattern of suspected hybrid warfare targeting critical infrastructure across the Nordic and Baltic region, raising alarm among members of the NATO military alliance.
Prime Minister Mette Frederiksen at the time described the incidents as the most serious hybrid attacks on the country's critical infrastructure to date but refrained from attributing responsibility directly.
Russia, which has regularly denied NATO accusations of mounting drone and online attacks in Europe, particularly since its invasion of Ukraine, said it had nothing to do with the incidents in Denmark at the time.
Justice Minister Nicolai Wammen on Thursday said the government and the authorities had taken the situation very seriously due to ongoing cyber attacks against European airports, airspace restrictions in Poland and an upcoming European Union summit in Copenhagen.
"It is part of the nature of hybrid warfare that the adversary does not reveal itself, and there may therefore be cases in the future where it is far from certain that we will be able to get answers to all our questions," he added.
In a separate report published last week, the Danish Armed Forces concluded that, based on soldiers' reported observations and technical information, drones had flown over Danish military installations a number of times during September 2025.
The armed forces said last week that responsibility for investigating and prosecuting any criminal conduct lay with the police.
