GAZA CITY, Gaza Strip (AP) — Israel carried out a blistering offensive of more than 20 airstrikes in the Gaza Strip on Wednesday, assassinating Hamas’ military commander and targeting the armed group’s training facilities and rocket launchers in Israel’s most intense attack on the territory in nearly four years.

Israel said the airstrikes, launched in response to days of rocket fire out of Hamas-ruled Gaza, were the beginning of a broader operation against the Islamic militants codenamed “Pillar of Defense.” Israeli defense officials said a ground operation was a strong possibility in the coming days though they stressed no decisions had been made and much would depend on Hamas’ reaction. There were no immediate signs of extraordinary troop deployments along the border.