Soon the Pope will be saying the US genocided the Native Americans.
That's a bit of a stretch. The aim of the US western expansion wasn't to kill all traces of Native American peoples and culture, it was to gain control of their land. While there certainly were numerous instances of massacres, they seemed to be more due to individual ignorance, prejudice, or misunderstanding than any systemic attempt to wipe out all Indians. Not even considering all the treaties and reservations set up (the quality-or lack thereof-of the land provided on the reservations can again I think be attributed mostly to apathy or ignorance as opposed to outright malice), the numerous attempts at integrating and Westernizing Native Americans shows a (misguided perhaps) desire to help them and make them become "Americans". In reality, the Western expansion was in effect a protracted, low-intensity guerrilla war, and there are plenty of cases of these types of conflicts to show that they very often lead to instances of overreactions of force, excessive non-combatant casualties, and mass killings.