The Danish Joint Arctic Command said it had evacuated a crew member from a US submarine in Greenland waters who needed urgent medical attention.
This happened seven nautical miles (about 13 km) from the capital of Greenland - the city of Nuuk, Reuters reported.
The man was handed over to Greenlandic health authorities and was admitted to the hospital in Nuuk, the command said in a statement.
The evacuation was carried out with the help of a "Seahawk" helicopter of the Danish armed forces, the message added.