In Gaza they began the moment the most recent ceasefire took effect. Here are some facts I have compiled since the end of Operation Protective Edge (OPE).
2.) HAMAS is hastily reconstructing critical tunnel infrastructure into Israel and Egypt with North Korean and Iranian assistance. They are driving medium-sized trucks through the largest tunnels between Sinai and Gaza loaded with rocket parts, ordnance and other munitions.
3.) Israel's military forces did not degrade HAMAS nearly as much as PM Netanyahu thinks they did. The political echelon led by Netanyahu did not cry havoc and cut loose their dogs of war (IDF) as should have been the case. As a result Israel very much lost this round of the war in Gaza because of politics. When the war resumes it will not only be Gaza but also a wide expanse of Sinai that Israel will have to deal with on the southern front.
"We are now in one of the tunnels of the Al-Quds Brigades [within] which work began as soon as the war on Gaza ended, and the ceasefire was declared. We have begun work and we are continuing it regardless of the threats by the Zionist enemy. We will not be hindered by the threats of the enemy, or by the ban on importing cement and other building materials. We are getting these tunnels ready for the next battle in order to launch attacks and fire mortars and artillery. These tunnels will also have other uses which we will not disclose."
LEBANON and the GOLAN
"Israel’s Iron Dome rocket defense system would not be able to cope with that kind of challenge, and thus the IDF would have to “maneuver fast” and act forcefully to prevail decisively in the conflict."
UPDATE 14 September 2014: Three hours ago DEBKAfile reported as Breaking News today's IDF briefing which contained a specific warning on the potential for Hezbollah incursions into northern Israel. These incursions could occur at virtually any moment from tunnels Hezbollah has constructed under the border with the same Iranian/North Korean expertise as seen in the Gaza tunnels, but which are also even more sophisticated that those in Gaza. The IDF has yet to discover even one of the tunnels Hezbollah is assessed to have constructed into northern Israel. Here's the Breaking news report:
"IDF Northern Command warns Hizballah plans invasion in next clash
DEBKAfile September 14, 2014, 9:57 PM (IDT)A senior IDF officer disclosed in a briefing Sunday that there is concern that Hizballah may provoke a clash with Israel and use it to seize territory – part of an Israeli town, a mountain ridge or an IDF outpost. There is no concrete warning that Hizballah is preparing to launch a surprise attack, said the officer, but the possibility cannot be discounted that a single event with casualties could spark a series of incidents leading to a conflagration. The officer said that the IDF has prepared contingency plans to evacuate border populations at risk."