In an official government statement released by the media on Tuesday, Switzerland's department of defence admitted it “misinterpreted” a communication from Paris over the issue.
The embarrassing incident came to light on Monday when it emerged that three Swiss Super Puma helicopters airlifted water from the Lac des Rousses last week as part of a Swiss army operation to replenish water supplies for Swiss cows suffering under the heatwave.
However local authorities in the French commune of Les Rousses, which owns the lake, had not granted permission for the action, which took residents and officials completely by surprise.
On Monday, the Swiss army claimed to have had the green light from Paris to go ahead with the July 22nd operation.
But after a meeting between the Swiss and French authorities, it appears the Swiss army got its wires crossed.
In a statement, the Swiss defence department said it had asked the office of the Swiss defence attaché in Paris for permission to fly over France for a period of three days, a request which was granted.
“France's flights HQ confirmed permission for the fly-over. The Swiss airforce misinterpreted this notification and authorized the airlifting of water from the Lac des Rousses even though such an action also required permission from the Jura prefecture,” said the statement.
“The Swiss army offers its apologies to the local and regional authorities, as well as to residents and tourists for any inconvenience caused.”
The action was part of an operation to rehydrate Swiss cows grazing in alpine pastures, where water was in short supply due to recent high temperatures.
The helicopter pilots asked to use water from France's Lac des Rousses because it was 15 minutes closer to the reservoirs than Swiss lakes including Lac de Joux and Lac de Neuchâtel.