Häber was one of the most influential foreign policy experts in the GDR, serving as the longtime head of the West Department at the Central Committee of the SED.

Afterward, he served as a sector leader until 1960 and, until 1965, as the head of the West Commission, a full-time employee of the Politburo of the Central Committee of the SED.

[1][3] The State Secretariat's task was to influence West German public opinion towards the SED's goal of a reunified Germany under their rule.

[4] The State Secretariat for West German Affairs was abolished in July 1971 as part of the SED's broader shift away from reunification.

[3] Häber subsequently served as the director of the newly established Institute for International Politics and Economics (IPW),[1][3] meant to research supposed imperialism in West Germany.

In May 1984, he was surprisingly made a full member of the Politburo of the Central Committee,[1][6]: 2300 [7][8][9][11][12][13][14][15][16][17][18] the de facto highest leadership body in East Germany,[7][8] and Secretary of the Central Committee of the SED,[1][14][19] responsible for International Politics and Economics,[6]: 2300 [14] succeeding retiring longtime Politburo member Paul Verner.

[1] In the early summer of 1984, Honecker pushed for his plans for a state visit to West Germany, previously rejected by Moscow.

[13][20]: 261 ff., 271–278  "The hidden threat from Chernenko, that deviating from the previous role of the SED as a follower of the CPSU could also have consequences for Honecker personally, prompted him to look for a scapegoat.

The geopolitical interests represented by Chernenko and Ustinov combined with Honecker's political self-preservation instinct, who had trusted and supported Häber until 17 August 1985.

Additionally, not only did the "Moscow faction" in the Politburo turn against Häber, but also the other members of the SED leadership did not resist his removal, which violated the statutes.

[7][8][13] The accused, as a member of the Politburo of the Central Committee of the SED, was deemed co-responsible for the deaths of three people shot at the former inner-German border, according to the court.

[7][8][13] This decision was based on the argument that during his tenure in the political leadership of the GDR, Häber had advocated for a moderation of the border regime, leading to significant, including personal, disadvantages for him.