The Gaza withdrawal is vital, despite the pain. That was the message from Israeli Prime Minister Ariel Sharon in a televised address to the nation. He declared that Israel couldn’t hold onto Gaza forever.“More than a million Palestinians live there,” he said, “.crowded in refugee camps, poverty and hotbeds of hatred with no hope on the horizon.” He spoke of the need to maintain national unity and said that the soliders implementing the pullout have the backing of the Israeli people. The premier also addressed concerns that Palestinians may step up violence after the evacuation, in the hope of obtaining more withdrawals. He vowed what he called “the harshest response ever” to any attack by militants. Ariel Sharon’s own political future largely depends on the success of the pullout. It has caused divisions within his Likud party and led to the resignation of his chief rival and former Finance Minister Binyamin Netanyahu earlier this month.