Because Machiavelli was blessedly free of simple-minded, unidimensional moralism, he could see the paradox that forsaking bloody actions for the sake of wanting to be loved can lead to greater bloodshed and cruelty later on. Particularly in the nuclear era, when the US can slay by the tens of millions at the push of a button, a great power cannot ever be position where it sees the situation as "Them or Us." Any state will choose "Them," and Hiroshima will look like a garden party. All for the sake of "Upholding Our Principles" some years earlier.
From the beginning of Chapter 17 of the Prince:
Descending next to the other qualities set forth before, I say that each prince should desire to be held merciful and not cruel; nonetheless he should take care not to use this mercy badly. Cesare Borgia was held to be cruel; nonetheless, his cruelty reconciled the Romagna, united it, and reduced it to peace and to faith. If one considers this well, one will see that he was much more merciful than the Florentine people, who so as to escape a name for cruelty, allowed Pistoia to be destroyed. A prince, therefore, so as to keep his subjects united and faithful, should not about the infamy of cruelty; because with very few examples he will be more merciful than those who for the sake of too much mercy, allow disorders to continue, from which come killings or robberies; for these customarily harm a whole community, but the executions that come from the prince harm one particular person. And of all princes, it is impossible for the new prince to escape a name for cruelty, because new states are full of dangers. And Virgil says in the mouth of Dido: "the harshness of things and the newness of the kingdom force me to contrive such things, and to keep a broad watch over the borders."¹Later in Chapter 17, Machiavelli makes the important distinction between being feared and being hated. Machiavelli notes that it is not only possible, it is even the best of all possible worlds, to have the first without the second. Americans don't understand that -- thinking that to be feared is to be hated. And, far worse, they don't understand that others do see things that way, particularly honor-based cultures such as the Arabs, to whom there is nothing more contemptible than weakness.
¹ I quoted from a translation other than the one I linked to, because Harvey Mansfield's translation of the Prince (the one I like best and the one the quote is from) is not available online.