President George W. Bush and Palestinian Authority President Mahmoud Abbas agreed in a telephone conversation Tuesday that if any new cease-fire agreement is to be effective in the Mideast, "it must be respected by Hamas," the White House said. Briefing reporters at Bush's Texas ranch, spokesman Gordon Johndroe reiterated the U.S. call for the militant Hamas organization to stop firing rockets into Israel. He said that Bush talked to both Abbas and Prime Minister Salam Fayed after having a briefing by videoconference with his own top aides on the fast-paced developments in Gaza. Johndroe said that "for any cease-fire to be effective, it must be respected by Hamas." Bush's spokesman added that in the absence of such a stance, a cease-fire agreement wouldn't be worth the "paper that it's written on." "The president is concerned about the citizens of Gaza," said Johndroe, "but not the Hamas terrorist leaders." "The only way that this is going to stop is if Hamas stops firing missiles" and all sides agree to a sustainable cease-fire, he added.