One of the recognised benefits to Britain from Swedish neutrality and independence during the Second World War was the ability of agents based in Sweden to gather intelligence from, and support resistance in, occupied Europe. Yet, all the belligerents maintained intelligence gathering in Sweden. The German Sicherheitsdienst (SD) and military Abwehr were there. British Secret Intelligence Service (MI6) and Special Operations Executive (SOE) were represented along with military intelligence. Following their entry into the war, the United States Office of Strategic Services (OSS, predecessor to the CIA) established themselves in Stockholm. The Soviet Union deployed the Russian Military Intelligence (GRU) and the State Security Section of the Council of People's Commissars (NKVD) — the instrument of Stalin's terror, which was reorganised constantly throughout the war and later became the KGB.

All of these organisations presented a threat to Sweden in one form or another. Most obviously, penetration of Swedish institutions by agents of these powers at best would reduce the ability of Swedish policy and decision-makers to conceal weaknesses and dissension. At worst, they could influence Swedish decisions in favour of their principals. Another risk to Sweden was that the belligerents would seek to destroy those assets in Sweden which they believed provided support to their enemy. Obvious targets were iron ore production, transit railways and military facilities. Military activity and resistance in adjacent Finland, Denmark and Norway raised the possibility of proxy conflicts on Swedish territory.