The Palestinian militant group Hamas (search) on Thursday threatened "an earthshaking response" against Israel for the assassination of the militant group's founder, Sheik Ahmed Yassin (search).

The threat was made by the group's military wing, the Ezzedine al-Qassam Brigades (search), in a videotape broadcast by the Al-Arabiya satellite channel.

The tape showed two masked men standing behind five tall rockets, the kind of missile that Hamas guerrillas use to hit Israeli towns. One of the men is reading a statement.

"Oh, masses of our Arab and Islamic nation, the sons of the struggling and steadfast Palestinian people in Palestine," the statement said, "the Ezzedine al-Qassam Brigades promise you that they will carry out a strong, earthshaking response and make the sons of monkeys and pigs taste a painful death in retaliation for the blood of our struggling people and the blood of our leaders, at the top of whom is the holy warrior and martyr Sheik Ahmed Yassin, may God have mercy on him."

Yassin, a quadriplegic, died Monday when an Israeli helicopter gunship fired three missiles as he was leaving a mosque in Gaza after dawn prayers. The Israeli government accused him of being an arch-terrorist who had planned attacks that had killed hundreds of Israelis.

Soon afterward, Hamas' military wing issued a leaflet saying the "terrorist American administration" had approved of the Israeli attack and "must take responsibility for this crime."

On Wednesday, however, Hamas distanced itself from the threat when a Hamas leader, Mahmoud Zahar (search), said the United States won't be targeted because Americans are "innocent of the Zionist conspiracy that is fooling you."

American, U.N. and Palestinian officials have said there was no indication Hamas changed its stance as a result of back channel pressures.

Hamas likely stepped back after realizing the potential consequences of the threat, said Joseph Alpher, an Israeli analyst. In addition, European countries would likely have enacted further sanctions against the group at the request of the United States, he said.

"My assumption is that Hamas understood that threatening the United States is liable to bring the United States ... to attack it," Alpher said. "The wiser heads prevailed here."

Thursday's statement promised to carry out attacks that Israel has not witnessed before "through al-Qassam rockets (search) with which we will hit all our occupied towns in Haifa, Jaffa and Ashkelon."

Yassin was born in the southern coastal town that is now called Ashkelon in 1934.

Referring to Israeli Prime Minister Ariel Sharon, the statement said: "We say to the pig Sharon that we will pound your fortresses and make you curse yourself 1,000 times for merely thinking of the assassination of our leaders."

Hamas' representative in Lebanon, Osama Hamdan, told The Associated Press in Beirut "the videotape is supposed to have come from inside Palestine." Hamas' military command is supposedly based in the Gaza Strip.

Hamdan said it was the first time in about 12 years that the military wing had issued a statement in a videotape.

In Cairo, Egyptian President Hosni Mubarak (search) said Thursday the "cruel" decision to kill Yassin would trigger violent retaliation.

Israel said after Yassin's assassination that it would target the rest of the Hamas leadership.

Such threats, Mubarak said, were "not a way to end violence, but to increase it inside and outside [Israel and the Palestinian territories], and in all the countries that support Israel," according to Egyptian Information Minister Safwat el-Sherif.