The background information on the civilization is here
In my world , where the entire "human" race is united, the age of colonization is under way, with certain clans making lots of headway.( Clans being the equivalent of mobile states without set geographic boundaries , much like the tribes in early Israel , but being able to uproot themselves , and move when needed) One clan , the Masimari , have substantial colonies in the "new world" , and have become discontent with the discourse of politics , and having to be subject to the laws of the primary government. ( asking themselves question like " are we not good enough to govern ourselves independently/" and "under what obligations are we to follow their laws?") They are now seriously considering seceding from the the union.
( The situation can be likened to the E.U. existing in the 16 and 17 hundreds [ with a power relationship with it component countries being between that of the modern E.U. and the U.S.] and Britain, with a growing sense of nationalism due to its colonial territory gains in the new world , attempted to exist the E.U. [ the difference in military power between the government and state is comparable to that of The U.S. and modern U.K. )
The main government does not what to start an armed conflict against the Masimari due to the fear that the clan will always remember this occasion with bitterness for generations , putting a permanent strain on their relationship.
My question is , In such a situation , is there any way that a central government with kind of authoritative control could subdue a rebelling state without armed force?
"The supreme art of war is to subdue the enemy without fighting" - Sun Tzu