Gaza: What Comes Next, Truce or Ground Invasion?

As the Israeli offensive heads into its sixth day and the missile strikes in Gaza continue, the international community has increased the volume on its call for a cease-fire.

A Palestinian woman gestures as others check the damage of their destroyed houses after an Israeli...

A Palestinian woman gestures as others check the damage of their destroyed houses after an Israeli missile strike at Rafah refugee camp, southern Gaza Strip. Thursday, Jan. 1, 2009. Israel demanded international monitors as a key term of any future truce with Gaza Strip militants, as its warplanes bombed the parliament building in Gaza City on Thursday and its ships attacked coastline positions of the territory's Islamic Hamas rulers.

(Khalil Hamra/AP Photo)
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Israeli warplanes struck 20 targets in Gaza overnight. The Israeli Air Force widened its targets to include Hamas' political institutions, its parliament and the Ministry of Justice. Israeli planes also hit the tunnels used for smuggling on the Gaza-Egypt border.

"Hamas government sites serve as a critical component of the terrorist groups' infrastructure in Gaza," Israel's Defense Force said in a statement.

An Israeli airstrike today hit the house of senior Hamas leader Nizar Rayyan, killing him, his wife and three children. Rayyan had refused to leave his house since the beginning of the Israeli offensive Saturday.

As of now, 26 Hamas rockets have been fired at Israeli cities. One was a direct hit on a residential building in Ashdod, about 17 miles north of Gaza. There were no casualties.

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This afternoon, the Israeli Air Force struck the underground launching post from which the rocket that hit Ashdod was launched. Israeli planes also targeted several weaponry storage facilities in Gaza.

Hamas Prime Minister Ismail Haniyeh spoke on local TV Wednesday night for the first time since hostilities broke out, detailing his conditions for a cease-fire.

"First, Israel must stop the aggression, lift the siege on Gaza and open the border crossings," he said, speaking from a bunker somewhere in the Gaza Strip.

Israeli Foreign Minister Tzipi Livni, who is a contender in next month's election to become Israel's prime minister, rejected any cease-fire, saying such a move at this time would only benefit Hamas.

In an interview with ABC News' chief Washington correspondent George Stephanopoulos, Livni said the cease-fire was unnecessary because Israel is keeping the border "crossings open during this operation" to allow "humanitarian aid to enter the Gaza Strip."

Inside Gaza humanitarian conditions are getting worse, with people waiting hours for bread alone. The number of dead in Gaza has risen to an estimated 400, with 2,000 injured. The U.N. special representative told ABC News Wednesday that the number of dead was between 320 to 390 -- 20 percent to 25 percent of them women and children.