Gaza: What does Israel's ground offensive aim to achieve?
Whatever the scope and duration of the Israeli ground offensive into the Gaza Strip a number of things are already clear. It will not end with the toppling of the Hamas regime or the re-occupation of Gaza by the Israeli army.
It will end in a truce brokered by outside players like Egypt. And the situation will return to what it was before this latest upsurge in fighting, at least until the next time.
So what then is Israel seeking to achieve by going into Gaza?
In the first instance the decision to give the green light to a ground phase may have a relatively limited objective - to seek out and destroy tunnels constructed by Hamas and other groups which they hope to use as a means of infiltrating heavily armed fighters into Israel.
One such operation was thwarted in the early hours of Thursday morning. Some 13 Palestinian fighters emerged from a tunnel between Kerem Shalom and Kibbutz Sufa, east of the Gaza Strip, at around 04:00 (01:00 GMT). Israeli troops quickly intercepted the intruders who took casualties and were forced back into the tunnel.
Infiltration attempts - either via tunnels or by landings on the Israeli coast - have been a relatively new tactic from the Palestinians in this crisis and Israel's Prime Minister Benjamin Netanyahu made an explicit reference to the tunnels when he announced his decision to give a green light to a ground mission.
If this is the initial driver of the operation then any incursion might be limited to the perimeter of the Gaza Strip with accompanying sea-borne raids.
However moving to a ground operation carries significant risks. For a start Israel's own forces could become vulnerable. The Palestinian fighters have a significant underground infrastructure and a number of relatively advanced anti-tank missiles. They will try to inflict casualties or seize individual soldiers to act as a bargaining chip.
But of course by far the greatest risk once heavy ground weapons become involved and there are localised firefights is to the civilian population.
This potentially could set a timeline for the operation since casualties will prompt ever greater international concern and pressure to halt any operation within as short a time period as possible.
In fact for all the Israeli talk about reducing Hamas's military infrastructure and so on, the Israeli military will be reluctant to go too deeply into densely populated areas.
If past experience is anything to go by Israel may seek to cut major roads and divide the Gaza Strip into zones within which its forces will operate.
But the primary aim is to bring pressure to bear on Hamas and other Palestinian groups to accept a ceasefire.
Israel does not want to take back control of the Gaza Strip. It wants a return to calm.
Israeli military analysts believe that Hamas is now on the back foot. Its efforts to take the battle to Israel through long-range rockets aimed at Israeli cities or by infiltration attempts have largely failed.
For whatever reason - and the inter-Arab politics and inter-Palestinian dynamics are complicating factors - no deal has so far been reached.
But that is the only way this struggle will end. And of course in a fundamental sense it will not end because Palestinian bitterness and sense of grievance will continue.
The impossible position of the Gaza Strip wedged between a hostile Egypt and Israel will continue. And in the absence of any broader peace initiative on the horizon, once Operation Protective Edge is over, the countdown will begin towards the next upsurge in violence.