On 2 September 1939, after the outbreak of war with Poland, Germany sent a solemn assurance to Norway in these terms:

"The German Reich Government is determined in view of the friendly relations which exist between Norway and Germany under no circumstance to prejudice the inviolability and integrity of Norway, and to respect the territory of the Norwegian State. In making this declaration the Reich Government naturally expects, on its side, that Norway will observe an unimpeachable neutrality towards the Reich and will not tolerate any breaches of Norwegian neutrality by any third . party which might occur. Should the attitude of the Royal Norwegian Government differ from this so that any such breach of neutrality by a third party occurs, the Reich Government would then obviously be compelled to safeguard the interests of the Reich in such a way as the resulting situation might dictate."
On 9 April 1940, in pursuance of her plan of campaign, Norway was invaded by Germany.

The idea of attacking Norway originated, it appears, with the Defendants Raeder and Rosenberg. On 3 October 1939 Raeder prepared a memorandum on the subject of "gaining bases in Norway", and amongst the questions discussed was the question: "Can bases be gained by military force against Norway's will, if it is impossible to carry this out without fighting?" Despite this fact, three days later, further assurances were given to Norway by Germany' which stated: "Germany has never had any conflicts of interest or even points of controversy with the Northern States and neither has she any today."

Three days later again, the Defendant Dönitz prepared a memorandum on the same subject of bases in Norway, and suggested the establishment of a base in Trondheim with an alternative of supplying fuel in Narvik. At the same time the Defendant Racder was in correspondence with Admiral Karls, who pointed out to him the importance of an occupation of the Norwegian coast by Germany. On 10 October Raeder reported to Hitler the disadvantages to Germany which an occupation by the British would have. In the months of October and November Raeder continued to work on the possible occupation of Norway, in conjunction with the "Rosenberg Organization." The "Rosenberg Organization" was the Foreign Affairs Bureau of the NSDAP, and Rosenberg as Reichsleiter was in charge of it. Early in December, Quisling, the notorious Norwegian traitor, visited Berlin and was seen by the Defendants Rosenberg and Raeder. He put forward a plan for a coup d'état in Norway. On 12 December the Defendant Raeder and the naval staff, together with the Defendants Keitel and Jodl, had a conference with Hitler,