In October 1965, in Accra, this resolution was adopted by the second ordinary session of the assembly of the heads of state and government;
AHG/Res. 27 (II)
DECLARATION ON THE PROBLEM OF SUBVERSION
The Assembly of Heads of State and government meeting in it Second Ordinary
Session in Accra, Ghana, from 21 to 25 October 1965,
Desirous of consolidating the fraternal links that unite us,
1. Not to tolerate, in conformity with article 3, paragraph 5, of the Charter, any
subversion originating in our countries against another Member State of the
Organization of African Unity;
2. Not to tolerate the use of our territories for any subversive activity directed
from outside Africa against any Member State of the Organization of African
3. To oppose collectively and firmly by every means at our disposal every form
of subversion conceived, organized of financed by foreign powers against
Africa, OAU of its Member States individually;
Notice that this is resolution #27 and the 26 earlier resolutions dealt with the internal works of the OAU (granting diplomatic immunity to its representatives etc..) or liberation/decolonization stuff (we condemn Apartheid, Jim Crow, Rhodesia and stuff) or even better thanking the host and with only resolution 10 and 17 have some sort of historical and political importance.
Now sure one could argue that the principle of non-interference and a quick mention of opposition to sedition were already in the charter but they felt the need to restate it and to devote an entire resolution to the “problem”.