An Israeli ground invasion into Gaza is 'highly likely' but risks escalating the conflict's humanitarian costs and bloodshed, says Middle East expert Nina Khatib. War erupted between Israel and Hamas at the weekend triggered by a bloody attack by Hamas militants, who killed 1,200 people in Israel and took around 150 hostages. Israel has retaliated with strikes claiming more than 1,300 lives, and has rushed forces, tanks and heavy armour to the southern desert areas around Gaza. IMAGES AND SOUNDBITES