GAZA CITY, Gaza Strip – 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.

The attack came at a time when Israel seems to be under fire from all directions. Relations have been deteriorating with Egypt’s new Islamist government, Egypt’s lawless Sinai desert has become a staging ground for militant attacks on Israel, and the Syrian civil war has begun to spill over Israel’s northern border. Earlier this week, Israel fired back at Syria – for the first time in nearly 40 years – after stray mortar fire landed in the Israeli-controlled Golan Heights.