Section, Gullberg, suspects that Prime Minister Olof Palme is a KGB agent. Whereas Poul Anderson's Max Abrams had substantial reasons to suspect the Merseians of duplicity (see here), the same might not be true in the case of Gullberg and Palme:
"To Gullberg's frustration, the question of Palme's possible Russian contacts was never resolved. Despite persistent attempts to establish the truth and uncover the crucial evidence - the smoking gun - the Section had never found any proof. In Gullberg's eyes this did not mean that Palme might not be innocent, but rather that he was an especially cunning and intelligent spy who was not tempted to makes the same mistakes that other Soviet spies had made. Palme continued to baffle them, year after year."
-Stieg Larsson, The Girl Who Kicked The Hornets' Nest (London, 2009), Chapter 5, p. 113.
Although, at first glance, Abrams might seem to be another Gullberg, there is a world of difference.