Vice Prime Minister Shimon Peres warned Saturday against isolating Palestinian Authority President Mahmoud Abbas, shortly after Prime Minister Ariel Sharon announced he will shun Abbas until he cracks down on terrorists, and after Defense Minister Shaul Mofaz told Yediot Aharonot Abbas is too weak and isolated to negotiate a peace deal. Peres said Israel could not afford to sideline Abbas. "When you say there is no partner, then only one partner is left, the terrorists. This is a mistake of the first order," Peres told Israel Radio. A few hours later, PA Interior Minister Nasser Yousef told his security chiefs that "firm and serious action" would be taken against facilities used to manufacture or store weapons, his office said in a statement released Saturday. But there was no talk of disarming terrorists, and the statement said Palestinian security forces "would not enter any house looking for weapons."