[horatio]

I think there were many layers, existential fear that their homeworld becomes uninhabitable, the fear of war and the fear of losing their identity in peace times (which was partly based on their misconception that they have to join the Federation to mae peace with them).

[Commodore]

The Klingons simply weren't in a position to continue hostilities with the Federation. They needed to concentrate more on saving Qo'noS and reorganizing their infrastructure than spend what now limited resources they had (at the time) maintaining a cold war. Had they gone that route, the Empire surely would have collapsed within 50 years as Spock warned...

[kevin]

Agreed on the economic side - it was clearly stated that because they spent so much of their money on the military they didn't have the resources to deal with the problems that Praxis' explosion led to.

If they could have coped themselves in the aftermath of the disaster - there would have been no peace talks