He was promoted to colonel in and was head of the Operation Command 2 of the Defence Staff in Ljung was promoted to lieutenant general in and was Chief of the Defence Staff from to The handling of the submarine incidents and the systematic continuing submarine incursions also caused great strain on him.
By then he had a close collaboration with Prime Minister Thorbjörn Fälldin and was very prominent throughout ljung dating incident. His report on the whole situation excluded the possibility that the submarine accidentally ended up in Swedish territory, and he pursue in the coming years the issue ljung dating higher allocations to the military to fight the submarine intrusions which was considered coming from the Soviet Union.
According to Robert Dalsjö's doctoral thesis, Ljung was the ljung dating Supreme Commander who knew the secret peacetime cooperation with NATOand also the one who discontinued the cooperation.
They had two children, Lars born a retired colonel and senior adviser of the Folke Bernadotte Academy  and Ann-Marie born