This week's Egyptian-hosted international conference on the reconstruction of the Gaza Strip underlined that the rehabilitation of Gaza is high on the international community's agenda. But the implementation of any rebuilding project may be premature. Indeed, given Hamas's ongoing weapons smuggling into Gaza, Israel's mid-January unilateral cease-fire may be short-lived. Although the United States and Israel reached an agreement on January 16 to counter the smuggling, Egypt and Israel have yet to forge a similar understanding. The persistence of Hamas's arms-smuggling almost ensures an eventual resumption of hostilities in Gaza. Beyond small arms, Israeli intelligence estimates that some 250 tons of explosives, 80 tons of fertilizer, 4,000 rocket-propelled grenades, and 1,800 rockets were transported from Egypt to Gaza from September 2005 to December 2008. According to Israeli figures, from June 2007 to December 2008, Hamas increased not only the quantity but also the quality of its arsenal in Gaza, improving the performance of its improvised explosive devices and expanding the distance and payload capabilities of its Kassam rocket warheads. Most small-range rockets fired from Gaza prior to and during the recent conflict were locally produced. However, over the past year, Hamas has acquired a formidable collection of imported 122-mm. rockets - the longer-range Grads - brought in piecemeal through tunnels and reassembled in Gaza. These Grads, an Iranian-produced version of the Chinese-designed rocket, increase the reach of Hamas into Israel, making them a sought-after commodity and well worth the effort and expense of smuggling them all the way from Iran. According to Israeli assessments, the arms-smuggling network is directed by Hamas offices in Damascus and aided by Iran's Islamic Revolutionary Guard Corps (IRGC), which provides the majority of the weaponry. The arms travel overland to Egypt through a variety of routes that cross Yemen, Eritrea, Ethiopia, and South Africa and eventually meet in Sudan, where they are moved to Egypt's Sinai desert. After the material enters the Sinai, it is transferred into Gaza via tunnels underneath the Philadelphi Corridor. Less frequently, arms are moved to Gaza via the Mediterranean Sea. The weapons are deposited in waterproof barrels submerged below the surface and tied to buoys eventually retrieved by fishermen. Despite recent improvements to the countersmuggling effort in the Sinai, Egypt is averse to recognizing the severity of the issue. Egypt's approach to countering Hamas's extensive network of smuggling tunnels has been tentative, generally limited to exposing tunnel openings and seizing weapons arsenals inside the Sinai Peninsula. In most cases, following the exposure of a tunnel, Egyptian forces have either placed a guard at the mouth of the tunnel or blocked the tunnel entrance, rather than taking steps to demolish the tunnel completely. As such, smugglers have been able to employ these tunnels again after a short interval. When a tunnel entrance has been blocked, diggers typically cut a new access channel nearby and connect with the existing tunnel closer to the border. In addition, there is no evidence that Egyptian forces are taking steps to arrest and punish smugglers. These rings are rarely broken up, and in the absence of lengthy jail terms, there is little deterrence. Moreover, cooperation between Egypt and Israel has been lacking. In mid-February, for example, Egypt announced it would not send a delegation to Israel as originally planned to discuss anti-smuggling and cease-fire negotiation efforts. Although Israel recognizes an effort is being made - Shin Bet (Israel Security Agency) chief Yuval Diskin told the cabinet on February 15 that Egyptian actions are indeed combating arms smuggling - Israeli officials note that the effort is, at best, "slow." Finally, the United States has provided Egypt with various technological devices - such as seismographic sensors - to expose the tunnels, but Egyptian forces still require training to make full use of these tools. It is imperative that Egypt recognize that arms smuggling is not just an Israeli issue but an Egyptian national security priority. The head of the Egyptian parliament's foreign relations committee said on December 3, 2008 that it would not allow an Islamic state on its northern border. If arms smuggling continues, however, such an outcome will become more likely. As such, Egypt needs to adopt a sustained and effective approach to its activities countering the movement of weapons from Sudan to the Sinai Peninsula, as well as the tunnels themselves. First, Egypt should close these tunnels for good rather than temporarily securing them. At the same time, Egyptian security forces should arrest smugglers, target their networks, and impose stricter penalties for these illegal activities. Finally, Egypt should better publicize these efforts to create a deterrent effect. More effective bilateral cooperation between Israel and Egypt, with US oversight and active involvement, should be initiated. Discussions between all three parties would go a long way toward increasing coordination and efforts to combat this threat. In this regard, the United States could play an important role as a watchdog, providing periodic reports on the effectiveness of Egyptian and Israeli action. Perhaps most importantly, the three countries' intelligence services should join forces and share information to successfully combat the Hamas weapons-smuggling networks. Much of the weaponry is provided by Iran, and specifically by the IRGC, increasing Iran's regional influence while threatening the position of Fatah in Palestinian politics. Dealing effectively with these tunnel systems could curtail Iranian influence. Conversely, if Gaza remains a terror base - a safe haven for extremists and global jihadists - regional instability and Palestinian suffering will surely grow. Yoram Cohen is a visiting fellow at The Washington Institute. Previously, he held positions in the Shin Bet (Israel Security Agency), serving until recently as deputy director. Matthew Levitt is the director of the Stein Program on Counterterrorism and Intelligence at The Washington Institute.