The chief care was bestowed in securing the communications between Spain and Africa: with that view the fleet remained in Spain, and western Africa was guarded by a very strong body of troops.

The fidelity of the troops was secured not only by hostages collected from the Spanish communities and detained in the stronghold of Saguntum, but by the removal of the soldiers from the districts where they were raised to other quarters: the east African militia were moved chiefly to Spain, the Spanish to Western Africa, the West African to Carthage.

Adequate provision was thus made for defence.

As to offensive measures, a squadron of 20 quinqueremes with 1000 soldiers on board was to sail from Carthage for the west coast of Italy and to pillage it, and a second of 25 sail was, if possible, to re-establish itself at Lilybaeum; Hannibal believed that he might count upon the government making this moderate amount of exertion.
With the main army he determined in person to invade Italy; as was beyond doubt part of the original plan of Hamilcar.

A decisive attack on Rome was only possible in Italy, as a similar attack on Carthage was only possible in Libya; as certainly as Rome meant to begin her next campaign with the latter, so certainly ought Carthage not to confine herself at the outset either to any secondary object of operations, such as Sicily, or to mere defence--defeat would in any case involve equal destruction, but victory would not yield equal fruit.
Method of Attack But how could Italy be attacked?
He might succeed in reaching the peninsula by sea or by land; but if the project was to be no mere desperate adventure, but a military expedition with a strategic aim, a nearer basis for its operations was requisite than Spain or Africa.
Hannibal could not rely for support on a fleet and a fortified harbour, for Rome was now mistress of the sea.