Israel withdraws from Gaza - leaving it to the Palestinians to govern and manage.
Palestinians choose a government committed to engaging in aggression against Israel and destroying it - Hamas
Palestinians engage in a small scale civil conflict splitting the government between Gaza and the West Bank, leaving Hamas in Gaza.
Hamas decides to make Gaza not a haven for peace, development, economic growth and freedom, but a base to wage war against Israel - indiscriminately firing rockets into Israel proper (you know the country that is internationally recognised, not occupied territories) killing and injuring Israeli civilians.
Israel puts up a blockade against Gaza to stop entry/exit of citizens across the land border, and stops selling electricity to Gaza as retaliation. Gaza still has an open land border with Egypt.
Israel is accused of being unreasonable, against those who wish to destroy it and attack it.
Hamas continues its bombardment, Israel responds by attacking bases in Gaza from where rocket attacks continue, killing 120.
Hamas sends a gunman in to shoot children at a school in Jerusalem.
So who wants to defend those who execute children for political purposes again?