The aerial bombings and the ongoing ground invasion of Gaza by Israeli ground forces must be analysed in a historical context. Operation "Cast Lead" is a carefully planned undertaking, which is part of a broader military-intelligence agenda first formulated by the government of Prime Minister Ariel Sharon in 2001: 

"Sources in the defense establishment said Defense Minister Ehud Barak instructed the Israel Defense Forces to prepare for the operation over six months ago, even as Israel was beginning to negotiate a ceasefire agreement with Hamas."(Barak Ravid, Operation "Cast Lead": Israeli Air Force strike followed months of planning, Haaretz, December 27, 2008)

It was Israel which broke the truce on the day of the US presidential elections, November 4: 

"Israel used this distraction to break the ceasefire between itself and Hamas by bombing the Gaza strip.  Israel claimed this violation of the ceasefire was to prevent Hamas from digging tunnels into Israeli territory.

The very next day, Israel launched a terrorizing siege of Gaza, cutting off food, fuel, medical supplies and other necessities in an attempt to “subdue” the Palestinians while at the same time engaging in armed incursions. 

In response, Hamas and others in Gaza again resorted to firing crude, homemade, and mainly inaccurate rockets into Israel.  During the past seven years, these rockets have been responsible for the deaths of 17 Israelis.  Over the same time span, Israeli Blitzkrieg assaults have killed thousands of Palestinians, drawing worldwide protest but falling on deaf ears at the UN." (Shamus Cooke, The Massacre in Palestine and the Threat of a Wider War, Global Research, December 2008)

Planned Humanitarian Disaster

On December 8, US Deputy Secretary of State John Negroponte was in Tel Aviv for discussions with his Israeli counterparts including the director of Mossad, Meir Dagan. 

"Operation Cast Lead" was initiated two days day after Christmas. It was coupled with a carefully designed international Public Relations campaign under the auspices of Israel's Foreign Ministry.

Hamas' military targets are not the main objective. Operation "Cast Lead" is intended, quite deliberately, to trigger civilian casualities. 

What we are dealing with is a "planned humanitarian disaster" in Gaza in a densly populated urban area.