They took five years to build, and just a few weeks to demolish. The IDF will pull ground forces out of Gaza over the next few days, leaving a lot of destruction behind, and perhaps not just a few questions for Hamas to answer once Israelis soldiers return to their side of the Gaza border:

The IDF has destroyed Hamas’s flagship terrorism project: its network of tunnels that snuck into Israel.

Hamas spent five years preparing this strategic threat; the IDF wrecked 31 tunnels in two weeks.

By Sunday, all of the tunnels that the IDF discovered during the offensive, or knew about before the war, will be destroyed.It is assumed that there are a few tunnels that the army has yet to identify.

Many of the underground passages were designed to send heavily armed murder squads into Israeli communities and to attack army positions from the rear. They were filled with weapons, explosives and other equipment, enabling terrorists to enter a shaft in Gaza dressed in civilian clothing and emerge in Israel, disguised as IDF soldiers and equipped to inflict mass casualties.

In some of the tunnels, the army discovered motorcycles that Hamas had earmarked for speedy raids into Israel and subsequent retreats back into Gaza.

Despite a unilateral cease-fire by Israel, Hamas continues to fire missiles northward. Israel has returned fire through airstrikes, which will also continue even after ground forces leave. Hamas also accused Israel of violating its own cease-fire, but that’s a rather hypocritical charge given that Hamas has refused any cease-fire unless totally on its own terms — and is firing rockets while complaining about Israel’s attacks.

After the IDF leaves and the war winds down, though, Hamas will face some difficult questions from Gazans. Why did they start this war in the first place? They will end up with nothing from it, not even a cease-fire on Egypt’s original terms, and now they’ve lost the tunnel system that Hamas built using the humanitarian aid that was supposed to benefit Gazans. No one in Gaza will see anything from five years of aid and the use of resources; the whole enclave has been set back at least five years, if not ten or twenty, because of a war that Hamas chose to provoke now rather than wait for the massive attack they had planned to conduct through those tunnels next month on Rosh Hashanah. The leadership of Hamas looks more incompetent than ever, and for a terrorist organization that rules by fear, the exposure of incompetence is usually fatal.

Israel will have some questions to ask itself, too. How did the tunnels get so advanced without their knowledge? The timing of the war seems rather fortuitous in retrospect, but that can’t make Israelis feel too comforted, especially those in reach of those tunnels. The IDF may have to answer for some target selections, too, such as the one yesterday in front of a UN school and refugee center. A missile strike on three militants succeeded in killing them — and another seven civilians standing at its gate. The UN official running the school angrily questioned why the strike took place at that location rather than a little farther down the road:

In Jersualem, a Palestinian backhoe driver got shot and killed after attacking a bus:

In Jerusalem, meanwhile, police said they were investigating an incident in which the driver of a backhoe apparently rammed a bus and overturned it Monday afternoon. Two people were injured, and the driver of the backhoe was shot and killed by police, according to police spokesman Micky Rosenfeld.

“We’re looking at this incident as a terrorist attack,” Rosenfeld said.

Jerusalem has been largely quiet since the killing last month of an Arab teenager, allegedly by Jewish extremists in revenge for the killing of three Israeli students in the West Bank, sparked days of unrest. But Monday’s incident could set the Israeli capital on edge as the battle in Gaza continues.

The IDF’s eventual withdrawal of ground forces from Gaza may help cool tempers in Jerusalem, but don’t count on them to cool too quickly.

Update: An Israeli airstrike killed the northern commander of Palestinian Islamic Jihad:

An Israeli airstrike killed a militant leader in the Gaza Strip on Monday, just hours ahead of an expected seven-hour truce announced by Israel that was meant to open a “humanitarian window” for aid.

However, the Israeli military said the cease-fire, which was to start at 10 a.m. local time (3 a.m. EDT) would not apply to areas where troops were still operating and where they would respond to any attacks.

The Islamic Jihad group – a close ally of Gaza’s militant Palestinian Hamas rulers – said its commander in the northern part of the strip, Daniel Mansour, died when the Israeli strike hit his home just before dawn Monday.

The war isn’t over yet. Israel is just returning to the higher-percentage strategy now that the tunnels have been demolished.