The National Maritime Authority has warned vessels to avoid part of the Great Belt strait for the risk of “falling missile fragments.” Ships have been asked to drop anchor if necessary.

A naval exercise began in the area last March and is due to end on Friday. The shipping lane was closed for 6 hours and later reopened on Thursday evening.

In a statement, the Danish Military said the problem with the missile occurred “during a mandatory test where the missile launcher is activated and cannot be activated.”

“Until the missile launcher is deactivated, there is a risk that the missile can fire and fly a few kilometers away,” the military added.

The missile was launched from the Niels Jeul frigate, which has been a part of NATO’s standing naval force since 2023.

The warning covered an area southwest of the town of Korsor, around 2.5 miles south of the Great Belt Bridge, which crosses the strait. The bridge remained open to traffic according to its operator.

The defense ministry said that the missile contained 150kg (~330 lbs) of explosives, adding that it was not armed and would not detonate if it crashed into the sea.

In a later statement, the ministry said that specialists had “carried out a number of different tests after which it was established that the booster was not armed and that there is no longer a risk that the missile can be launched.”

The incident in the Great Belt strait comes at the end of a tough week for the Danish Navy. On Wednesday, the chief of defense, Gen Flemming Lentfer, was sacked for failing to report a malfunctioning weapons system on a Danish Frigate, the Iver Huitfeldt, in the Red Sea. Denmark’s defense minister, Troels Lund Poulsen, said he had lost his trust in Mr. Lentfer, who did not inform the defense ministry that the frigate’s radar and missile systems failed as it came under attack from a drone controlled by Houthi militants. The Iver Huitfeldt was helping to safeguard commercial sea traffic from Houthi attacks as they launched a campaign of support for Palestinians following Israel’s offensive in Gaza.

Neither the crew nor the ship were harmed during the deployment.