Is Ace Combat 8 connected to earlier Ace Combat games?
Yes at the setting level: it takes place in Strangereal and uses established series concepts, but every direct historical connection has not been mapped publicly.
Confirmed explanation
The 2029 FCU–Sotoa war is a new central conflict. Licensed aircraft and a preorder port of Ace Combat Zero are not themselves proof that the two campaigns share a direct plot.
What is not confirmed yet
Returning characters, precise continuity references and the full geopolitical timeline remain unconfirmed.