The United States is blaming the Palestinian militant group Hamas for breaking a cease-fire and attacking Israel, which retaliated with airstrikes that have left more than 200 people dead. U.S. officials called for a restoration of the cease-fire and urged Israel to avoid civilian casualties. 

After the bloodiest day of Mideast fighting in years, the White House called for the cease-fire to be restored.

White House spokesman Gordon Johndroe said it was "completely unacceptable" for Hamas, which controls Gaza, and which the United States considers a terrorist organization, to launch attacks on Israel after a truce that lasted six months.

Johndroe said Israel has a right to defend its people against terrorists, and he called Hamas "nothing but thugs."  He also called on Israel to avoid civilian casualties. "Israel has said that they are targeting security and headquarter elements of Hamas. We have asked and urged Israel to avoid civilian casualties. We want the cease-fire to be restored. But we understand that Israel is reacting to the hundreds of rockets that have been fired upon the innocent people of Israel over the last few days," he said.

Johndroe spoke from Texas, where U.S. President George Bush has been spending a Christmas vacation at his ranch. 

Johndroe also said President-elect Barack Obama, who is on vacation in Hawaii, was receiving security briefings on the situation in Gaza.

U.S. Secretary of State Condoleezza Rice said she holds Hamas responsible for breaking the cease-fire that ended last week and for the renewal of violence in Gaza.  She said the cease-fire must be restored immediately and called on all concerned to address the urgent humanitarian needs of Gaza.