Der fremkom jo også i de år fra tysk side ofte bebudelser af nye afgørende våben. Ved møderne med Jensen var jeg ligeledes yderst tilbageholden som følge af den stadig voksende spionering fra det tyske politis side.

Da jeg, for at undgå en umiddelbart forestående arrestation, måtte flygte til Sverige i efteråret 1943 og derfra kom til England, lærte jeg for første gang om det da allerede vidt fremskredne amerikansk–engelske atomprojekt. Spørgsmålet om, hvor langt man var kommet i Tyskland, optog ikke alene fysikerne, men også regeringerne og efterretningstjenesten, og jeg blev inddraget i drøftelserne derom. Jeg fortalte om alle vore oplevelser i København, i hvilken forbindelse også spørgsmålet blev rejst, hvad bemyndigelse der fra den tyske regerings side måtte være givet dig til at berøre et så farligt spørgsmål, med så store politiske konsekvenser, over for nogen i et besat og fjendtligt indstillet land. Drøftelserne fik dog ikke nogen afgørende betydning, hverken i den ene eller anden retning, idet det, på basis af efterretningstjenestens oplysninger, allerede da var ret klart, at der ikke i Tyskland var mulighed for at gennemføre et så stort foretagende førend krigens afslutning.

Jeg har skrevet så udførligt for, så godt jeg kan, at belyse hele sagen over for dig, og håber, at vi ved lejlighed kan tale nærmere sammen derom.

In those years there were often announcements from Germany of new and decisive weapons. At the meetings with Jensen, I was likewise extremely cautious as a result of the constantly growing surveillance on the part of the German police.

When I had to escape to Sweden in the autumn of 1943 in order to avoid imminent arrest and from there went to England, I learned for the first time about the already then well-advanced American–English atomic project. The question of how far Germany had come occupied not only the physicists but also the governments and the intelligence service, and I became involved in the discussions about this. I recounted all our experiences in Copenhagen, and in this connection the question was also raised about what authorization might have been given to you by the German government to touch upon such a dangerous question, with such great political consequences, with someone in an occupied and hostile country. However, the discussions had no decisive influence one way or the other, since it was quite clear already then, on the basis of intelligence reports, that there was no possibility of carrying out such a large undertaking in Germany before the end of the war.

I have written at such length to make the case as clear as I can for you and hope that we can talk in greater detail about this when the opportunity arises.