Denmark closed a shipping lane in the Great Belt, a key route to the Baltic Sea, warning of the risk of missile fragments from a nearby military exercise.

A faulty missile launcher caused the problem during a mandatory test, the Danish military said in a statement. There’s a risk of a missile being fired as the launcher cannot be deactivated, it said.

A “danger area” is estimated to reach about 7 kilometers (4.3 miles) from Naval Station Korsor at a height of about 1,000 meters (3,300 feet) toward the south — away from the Great Belt Bridge.

Ships in the direction of the danger zone have been notified and asked to wait until the problem has been resolved, with specialists on their way to solve the problem, the military said.