The First War was a kind of slide into war, with a series of blunders and diplomatic slips that caused the two to go to war. This is in line with the thinking of Richard Miles in Carthage Must Be Destroyed.

The Second War is a bit more complex. Tensions had been building for a while. The Carthaginians in Spain (led by Hannibal, who, along with his father, had arguably ruled the Carthaginian territories in Spain as a sort of fiefdom) besieged Saguntum. Now, at the end of the First Punic War, the Romans and Carthaginians had agreed to create two separate spheres in Spain, divided by the River Ebro. Saguntum lay to the south of the Ebro but was a Roman protectorate. Hannibal viewed this as an aggressive action and so besieged it. This led to an ultimatum from Rome to the Carthaginians (told very dramatically in Livy and Polybius) which essentially stated that Hannibal should withdraw or face war. Hannibal did not withdraw and so war began between the two states. This therefore can largely be determined to be the fault of the Romans, who broke the treaty signed at the end of the First Punic War. The relationship between the Romans and their protectorates was one relying both on fides and salus - Rome had to intervene on behalf of Saguntum to keep fides (faith) in their allies and also salus (safety) because it was essentially a direct attack on Rome itself.

The Third War was probably entirely caused by Rome, who wanted to destroy the much-reduced city-state that Carthage now was. There was no way that Carthage, whose fleet was now reduced and occupied not much more than modern-day Tunis, could have posed a threat to the global hegemon that was Rome.