In theory, requiring full scale war disincentivizes war, so a peaceful solution is more likely. If targeted assassinations became the norm, you'd probably end

In theory, requiring full scale war disincentivizes war, so a peaceful solution is more likely. If targeted assassinations became the norm, you'd probably end up in a scenario where the country with the most advanced assassination techniques could exert much more influence since they wouldn't have to try and justify it to their own population. The most powerful country would basically be a vengeful god; completely untouchable and capable of smiting anyone that doesn't fall in line.