Since the agreement on the tahadiyeh (lull) was reached between Hamas and Israel on June 19, the border crossings between Israel and Gaza have already been closed six times in response to Palestinian rocket fire. Israeli officials acknowledge that none of these attacks was carried out by Hamas. Hamas, nevertheless, is keeping itself busy. The organization's military wing is putting in place preparations based on a comprehensive strategy for facing an expected eventual large IDF operation into Gaza. Hamas gunmen are training extensively to play their allotted roles within this strategy. The model for Hamas is Hizbullah's preparations for and conduct of the Second Lebanon War in 2006. The evidence suggests that Hamas is using its uncontested control in Gaza to effect a qualitative change in its abilities and ambitions. Hamas's strategy derives at the highest level from the group's muqawama (resistance) doctrine. According to this view, Israel's Achilles' heel is its inability to absorb large numbers of military and civilian casualties. Hamas believes Israel's will can be broken through attrition and a steady toll of unexpectedly high numbers of both military and civilian casualties. In the event of a major IDF incursion into Gaza, Hamas would seek to maintain a steady rain of rockets on Israeli communities around the Strip and to break the sense of armored and air invulnerability hitherto enjoyed by Israeli forces engaging with its fighters. Hamas would of course also try to inflict steady losses of 4 to 10 casualties per day on IDF's ground forces during the fighting. Looking to the 2006 model, the movement's planners believe that achieving these goals could be sufficient to break Israel's will. To make this possible, Hamas is feverishly training as well as acquiring relevant weapons systems - of a type far superior in quality to those previously associated with the organization. The weapons systems on which Hamas is thought to be currently training in the Gaza Strip include a wire-guided anti-tank missile, probably the AT-3 Sagger, and additional anti-tank guided missiles: the AT-4 Spigot, the tripod-fired AT-5 Spandrel and the shoulder-fired AT-14 Spriggan - all useful against armor. All these systems have ranges of several kilometers. In addition, Hamas is thought to have brought into Gaza large numbers of RPG-29 Vampir handheld anti-tank grenade launchers with a range of 500 meters, which are capable of penetrating reactive armor and are considered far superior to the RPG 7 systems used by the movement in the past. Hamas is also developing improvised explosive devices, i.e. bombs. The organization possesses an Iranian-developed, locally-produced system known as the Shawaz explosively-formed penetrator that it says can penetrate 20 cm. of steel. Hamas also claims to possess air defense missiles, though no information could be obtained on their nature or the veracity of the claim. Imports from Iran and Syria and local production are all playing a role in the movement's development of its arsenal. In addition to arming Gaza to the teeth, Hamas is recruiting fresh fighters. Once again, the model is Hizbullah, and the intention appears to be to develop a force part-way between a regular army and a guerrilla force, of the type developed under Iranian tutelage by the Shi'ite Lebanese group. Extensive recruitment has been taking place in the past month. New fighters have been accepted to both the Izzadin Kassam Brigades - Hamas's long-standing military wing, and to the Executive Force - the newer group created since Hamas's election victory in January 2006. The latter force played the key role in Hamas's rout of Fatah in its 2007 coup. Hamas claims to have around 20,000 men under arms, though some sources suggest that the number may be higher. Again, both Iran and Syria are thought to be playing a role in providing advanced training to cadres from both of these organizations: around 1,000 Hamas men are thought to have trained in one of these countries in the last months. What does Hamas's attempt to create "Fortress Gaza" mean? Its political leaders have consolidated their rule internally vis-Ã -vis other Palestinian forces. They are thought to face a certain problem from yet more radical Sunni Islamist currents among both the rank and file fighters and commanders of their own military organizations. But for the moment, with no serious internal challenge, Hamas is digging in. The Hamas rulers believe that Israelis want only peace and quiet, which makes them both vulnerable and deterrable. Thus, Hamas is seeking to create a solid shield around its Gaza fiefdom that can be turned into a weapon of attack at a time and situation of its choosing.