The Israel Defense Forces opened Operation Pillar of Defense with an airstrike on a car carrying the head of Hamas’ military wing Ahmed Jabri. More airstrikes quickly followed and are believed to have targeted other top Gaza-based terrorists and their weapons caches. Update (12:25 PM): The IDF has released video of the strike.

An IDF spokesman stated on Twitter that the opening round of airstrikes targeted 20 sites and sought to destroy stockpiles of longer-range Iranian-supplied missiles that Hamas has smuggled into Gaza. One report stated that the air force struck a warehouse containing Iranian-supplied Fajr missiles.

U.S. ambassador to Israel Dan Shapiro reiterated ”Israel’s right to defend itself and its citizens from these attacks” three days ago. The Obama administration has yet to comment on these latest events.

Update (11:28 AM): Israeli media are reporting that the IDF is sending emergency call-up notices to reservists. IDF General Yoav Mordechaitold Channel 2 news ground troops may be sent into Gaza: ”There are preparations, and if we are required to, the option of a entry by ground is available.”

Israeli artillery has joined the air force in hitting targets in Gaza and eyewitnesses report that multiple Israeli naval vessels have appeared along the coast of Gaza.

Update (8:09 PM): The New York Times was unsure of how to cover the attacks:

Despite the launching of more than 800 rockets from Gaza into Israel in 2012—including hundreds in the past week—the Times expressed uncertainty about whether any rockets have been fired at all. The Israeli military operation that commenced today is “in response to what Israel called repeated rocket attacks,” according to the Times.

The Times is also uncertain about the nature of Hamas, a U.S.- and Israeli-designated terrorist organization. The Times reports that Hamas is a “militant organization regarded by Israel as a terrorist group sworn to Israel’s destruction.”