A Russian frigate fired two flares ‌towards a Danish military helicopter in international waters off the coast of Denmark, narrowly missing the ​aircraft on Monday, the Nordic NATO ​member’s military said.

The Fennec military helicopter had been on ⁠a routine mission to photograph the ​Russian frigate, the Danish defense command said in a ​statement late on Monday.

One of the flares passed close to the helicopter, it said.

Flares are pyrotechnics usually ​used as a warning signal at ​sea.

Denmark’s Foreign Minister Lars Lokke Rasmussen called the incident “unacceptable” ‌and ⁠said it could have endangered human lives.

“For our part, Denmark is working to ensure that all shipping can pass peacefully through ​Danish waters, but ​Russia ⁠is gradually moving the line for what it considers acceptable behavior,” ​he said in a statement on ​Tuesday.

He ⁠added that he had summoned Russia’s ambassador to Denmark for a meeting.

The Russian embassy ⁠did not ​immediately respond to a ​request for comment outside regular office hours.