Israel's return to the northern Gaza settlements of Dugit, Nisanit and Elei Sinai this week, as well as the 30th anniversary of the Entebbe raid, served as the backdrop for the IDF's intensification of its search for captured Cpl. Gilad Shalit in the Gaza Strip. Almost two weeks have passed since Shalit was grabbed by Palestinian gunmen in an attack at Kerem Shalom, and he has not been heard from since. "Operation Summer Rains," which started as a pinpoint mission to retrieve him, has now brought the IDF back to the former settlements, almost as if Israel never withdrew from Gaza 11 months ago. That withdrawal, officers and intelligence experts explained this week, not only enabled a massive terror build-up there, but also impaired intelligence capabilities, as demonstrated by the IDF's difficulty in finding the kidnapped soldier. That frustrating search is only a stinging reminder of what Israel accomplished in the past - flying troops 3,800 kilometers to surprise terrorists in a foreign country and save more than 100 hostages. The anniversary raises one daunting question: How is it that a country which managed to bring back hostages from Africa seems at a loss to find a soldier being held practically on its doorstep? "It's all about intelligence," one IDF officer heavily involved in the Gaza operations said this week. "Sometimes you have it, like at Entebbe, and sometimes, like now in Gaza, you don't." ONE REASON is that disengagement led to traditional sources of information drying up. Before Israel withdrew from Gaza last summer, former OC Southern Command Maj.-Gen. (res.) Doron Almog said Thursday, dozens if not hundreds of Palestinians were working as agents for the Shin Bet (Israel Security Agency) and Military Intelligence. Now, while their numbers might still be as high, access to them and the vital information they possess has been reduced. "There is no doubt that disengagement diminished our ability to gather intelligence," Almog says. "When the IDF was in Gaza we had daily contact with our agents. Now that's impossible." There are three basic methods for gathering intelligence: In military jargon, they're referred to as HUMINT (human intelligence), ELINT (electronic listening devices on telephones and computers) and surveillance of a target - by camera, unmanned aerial vehicle (UAV) and satellite. Since last summer, Israel has developed a highly-advanced system of sensors along the border with Gaza. While they did not help in preventing the deadly attack against Shalit's outpost, they have assisted troops in thwarting numerous infiltrations from the Palestinian territory into Israel. Part of the reason the sensors may have failed to help find the missing soldier, one security official explained, was that the kidnappers were probably keeping off their cellular phones and the Internet. "The kidnappers are doing a very good job at disconnecting themselves from the rest of the world," Almog explained. Shalit, he said, could also be locked up inside an underground bunker or in a home that cannot be seen by UAVs or satellites. WITHOUT ELECTRONIC or surveillance intelligence, one of the only ways left to find Shalit, Almog said, was to operate human agents on the ground who can collect intelligence for Israel. That seems to be happening. Earlier this week, a Hamas official appeared on Al Jazeera television claiming that Shin Bet agents were interrogating doctors and pharmacists throughout the Gaza Strip, hoping to glean information from someone who might have treated Shalit, who was wounded during his abduction. The Hamas official claimed Israel was wasting its time and would never find the kidnappers' hideaway. Nonetheless, one defense establishment assumption is that the ultimatum set by the kidnappers on Tuesday was motivated by a feeling that the noose was tightening around their necks and that Israel was closing in on them. Almog, who was the first soldier to jump off the Hercules plane in Entebbe and the last to board it, says that in Uganda, Israel had the element of surprise and it was therefore easy to collect intelligence. "They never thought we would launch such an operation and we caught them off guard," he said. "In Gaza, however, the terrorists know we can get to them and that is why they are being extra careful not to leave any intelligence signatures and by minimizing their contact with the outside world."