Israel's air force attacked targets in the Gaza Strip on Saturday, witnesses said.
Following are some key facts about the Gaza Strip.
WHERE IS GAZA?
* The Gaza Strip is a sliver of towns, villages and farmland at the southeast end of the Mediterranean, 45 km (25 miles) long and at most 10 km (6 miles) wide. It is wedged between Israel to the north and east, and Egypt's Sinai Peninsula to the south.
HISTORY OF THE TERRITORY:
* Gaza city has been continuously inhabited for more than 3,000 years and was a crossroads of ancient civilizations. It is believed to be the burial place of the Prophet Mohammad's great grandfather.
* Four centuries of rule by the Ottoman Empire were briefly interrupted by Napoleonic France and also saw growing Egyptian influence until Britain took control of Gaza and the rest of Palestine in World War One. Egypt took control of the Strip during the 1948 Arab-Israeli war.
* The Strip's population tripled in 1948-49 when it absorbed about a quarter of the hundreds of thousands of Palestinian refugees displaced from areas that are now part of Israel.
* Israel captured the Gaza Strip from Egypt in the 1967 war.
* Israel pulled Jewish settlers and soldiers out of the territory in September 2005.
* Israel conducted large-scale ground operations in June 2006 after militants tunneled across the Gaza border and captured an Israeli soldier, who is still being held.
* A year later, Hamas Islamists took control of the Gaza Strip after routing President Mahmoud Abbas's Fatah forces.
* Israel tightened the closure of its borders with Gaza, curbing fuel supplies and limiting movement of people. International organizations have condemned the blockade, which Israel says is meant to curb rockets fired by militants.
* Under an Egyptian-brokered ceasefire in June, Hamas agreed to halt rocket fire in return for Israel easing the blockade. Hamas declared the end of the truce on December 18.
WHO LIVES THERE?
* About 1.5 million Palestinians live in Gaza, more than half of them refugees from past wars with Israel. Gaza has one of the highest population densities and demographic growth rates in the world.
* Most Gazans live on less than $2 a day and up to 80 percent are dependent on food aid, according to aid groups.
(Writing by David Cutler, London Editorial Reference Unit; Editing by Timothy Heritage)