Christmas holidays of 1951, and Enbom was arrested on 16 February 1952. During interrogation, he confessed that he—from February 1943 to April 1951—had met with Soviet employers around 25 times. Enbom had provided a large variety of intelligence, most of it from public sources, but also secrets, of which the armament of one of the forts in the fortress was one of the pieces of information that concerned Boden Fortress and nearby fortifications. He was sentenced to lifetime hard labour, but was released after ten years. The other case involved Ernst Hilding Andersson, who was arrested on 21 September 1951. He had carried out seven missions for the Soviets and had provided them primarily with information regarding the Swedish Navy, but also information on the fortifications along the Norrland coast, and an initiated report about Boden Fortress and the airforce unit located in Boden and Luleå, Norrbotten Air Base Corps. Andersson was, like Fritjof Enbom, sentenced to hard labour for life. End and aftermath Cold War and decommission The fortress was gradually modernised in the decades following the Second World War, including newer main artillery for some of the forts and newer secondary artillery for all forts as well as other improvements. But the development of new weapons and the evolution of warfare during the Cold War gradually decreased the importance of the fortifications. Weapons such as cruise missiles and smart bombs made large static fortifications such as Boden Fortress obsolete when they demonstrated their worth during the Gulf War in 1991. Mjösjöberget Fort had been decommissioned and removed from the wartime organisation twelve years earlier in 1979, and less than ten years after the Gulf War and the collapse of the Soviet Union, the four other forts followed suit. The last shot was fired from Rödberget on 14:11 local time on 31 December 1997, and exactly one year later, on 31 December 1998, that last fort was decommissioned after 90 years in service. All five forts and three battery positions—Leåkersberget, Norra Åberget and Södra Slumpberget—were declared historic buildings in the summer of 1998 and are to be preserved for the future. The balloon hangar, the only of its kind in Sweden, was declared a historic building three years later in 2001. Two forts, Rödberget and Södra Åberget, are held in operation, and the former is used as a tourist attraction with guided tours, and there is also a possibility