Hamas regards Israel as the party that started hostilities with the Palestinians and continues to provoke them. Yassin cited the dispossession of Palestinians from their land -- he was born in the village of Askalan, which today is the Israeli city of Ashkelon -- and the death toll of Palestinians at the hands of Israeli soldiers and settlers.
"Islam gives me the right to behave with my enemy as my enemy behaves to me," he said. "If he kills civilians, it is our right to kill their civilians."
Minutes after speaking of a truce, Yassin was asked whether he would agree to a request from Arafat to halt all "military operations" against Israel.
"I have said many times that we are defending ourselves against occupation," he said. "The occupation continues, so there will be struggle. It will stop only when the occupation is removed from all our land and all our people."
Ziad Abu Amr, a Palestinian legislator and political scientist, said Hamas is above all a mass political movement, and Yassin's language is aimed at appealing to varied constituents -- the Palestinian majority that wants to give peace a chance, the Hamas hard core that wants to fight, and even parts of the Israeli and international publics. By focusing his demands on the Palestinian consensus -- statehood for the territories captured by Israel in the 1967 Middle East War -- Yassin undercuts efforts by some of those around Arafat to portray him as an extremist.
Senior functionaries of Arafat's self-rule authority, who anticipated with some anxiety that Yassin would mount a frontal attack on his secular rivals, have welcomed his most moderate comments and tended to interpret them in the softest light.
"We feel relieved that the statements of Sheik Ahmed Yassin are very logical, sensible," said Aown Shawa, Arafat's handpicked mayor of Gaza City. "When Sheik Yassin says he wants Israel to evacuate the West Bank and Gaza and permit a Palestinian state with East Jerusalem as its capital, it means he accepts coexistence with Israel."
But others among the Hamas leadership take a harder line. Abdel Aziz Rantisi, the senior political leader of Hamas in Gaza, arranged for posters of Emad Akel and Yehiya Ayash -- slain leaders of Hamas's Issadin Kassem military wing, responsible for scores of deaths in Israel -- to be put on prominent display at the welcoming ceremony for Yassin's return to Gaza.
And Meshal, the Hamas leader in Jordan, said in reply to talk of a truce that "Hamas will not recognize the state of Israel even if it withdrew from Palestinian lands occupied in 1967."
Yassin's resonance as a national symbol rivals Arafat's, even among secular Palestinians. Tariq Abu Daya, a clerk at the PLO Flag Shop in Gaza City, said he has sold 5,000 Yassin pennants bearing the slogan "Islam is the answer." The pennant costs more than $4, which is not an insubstantial sum in Gaza's sprawling slums.
Israel's decision to free Yassin made it difficult for Arafat to continue his first serious crackdown on Hamas since early 1996. After Israel identified the suicide bombers in two summer attacks as coming from the West Bank, Arafat had arrested about 80 Hamas leaders and closed down 16 Islamic associations run by the fundamentalist group.
Those days are over. Last week Tayeb Abdul Rahim, Arafat's senior lieutenant, held a "unity meeting" with Hamas and formed committees to discuss the release of the prisoners and reopening of the associations.
"Those who are innocent, who didn't commit any security violation, are going to be released for sure," Maj. Gen. Nasser Yusef, the top Palestinian security official, said in an interview. As for the Islamic associations, he said, "I don't think there was a need for closing them."