The Danish The military have shut down their air space and shipping routes after a missile failure that happened on a naval ship.
The National Maritime Authority has given a warning because there is a risk of 'falling missile pieces' following the failed launch close to the busy Great Belt Bridge.
The Norwegian Defence Ministry said the missile had 150kg of explosives, but it is not armed and will not explode if it crashes.
In a statement, the military said: 'Experts are on their way to fix the problem. Until the booster is disabled, there is a chance that the missile could launch and fly several kilometers away.
'The police and the Danish Maritime Authority are informed, and ships going towards the danger zone are told to wait for the problem to be solved. The air space in the area is also closed.'
The warning also includes the town of Korsor, which goes across the strait.
Ships have been advised to drop anchor.
Flight Radar seems to show only a few planes in the air space around the affected area.
The Great Belt Strait is one of the busiest waterways in the world, connecting the North Sea and Baltic Sea.
The route used for shipping goes back to the Roman Empire, with historian Tactacus describing it as a 'large salty sea to the far north'.
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