Israeli forces have begun an incursion into the Gaza Strip following an exchange of rocket fire from Gaza and Israeli airstrikes over the last ten days.

According to a statement by Israeli Prime Minister Benjamin Netanyahu, the purpose of the operation is to destroy the Hamas-built tunnels leading into Israel, one of which was used by Hamas to infiltrate Israel earlier today. The Hamas mission was uncovered and disrupted by Israel Defense Force troops just a mile outside of a kibbutz in southern Israel. 

The IDF dropped leaflets warning citizens of Gaza's major cities to evacuate their homes before launching a series of air and artillery strikes on Thursday night. 

IDF Spokesman Peter Lerner confirmed the mobilization and made the case for the operation against the tunnels.

Hamas for its part is also talking tough:

Hamas spokesperson Fawzi Barhoum says that the IDF ground invasion of the Gaza Strip “is a dangerous action and the Occupation will pay a dear price for it. Hamas is prepared for this operation."

The escalation comes just after a brief five-hour humanitarian ceasefire was observed (minus three Hamas mortars) by the two sides earlier today.

The ground invasion of Gaza by Israel is the first such maneuver since Israel and Hamas did battle in 2009. In that conflict, the ground invasion marked a turning point in what was already a controversial war with much higher civilian death tolls. 

There are a number of things that are different this time around. 

A Different Rationale

The rationale for the 2009 invasion, which came after an eight-day aerial offensive by Israel, was this:

To strike a direct and hard blow against the Hamas while increasing the deterrent strength of the IDF, in order to bring about an improved and more stable security situation for residents of Southern Israel over the long term.

As surreal as it sounds, Israelis may look back on the 2009 conflict with longing as it was a time in which only the southern part of Israel was within range of Hamas and other terrorist groups firing rockets from Gaza.

Part of what's forcing Israel's hand here is that this conflict has placed five million Israelis within Hamas' reach, including cities like Jerusalem, Tel Aviv, and even communities in the north. 

A Different Prime Minister 

During the last ground invasion, Israel's prime minister was Ehud Olmert. For all the knocks on current Israeli Prime Minister Benjamin Netanyahu, he is thought to be considerably more cautious about the use of force than Olmert was (see: the 2009 Gaza War and the 2006 Second Lebanon War). 

Just days ago, Netanyahu fired Danny Danon, his deputy defense minister, after Danon essentially called him soft on Hamas for endorsing the Egyptian-proposed ceasefire that Hamas rejected. Others in Netanyahu's cabinet have said some pretty outlandish things including Foreign Minister Avigdor Liberman, who called for a full reoccupation of Gaza, which Israel fully withdrew from in 2005.