Saul committed genocide on the Amalekites, and it was a righteous act.
G-d spoke to Moses and said that that would be required. Saul failed in this Divine command, and let the king of the Amalekites live for one night, and he used that opportunity to plant his seed in a lowly serving maid who was in the slammer with him. From that came Haman, among others.
Nobody knows who the Amalekites are now. Genocide of Palestinians would not be justified, and has never been an Israeli goal.