The IDF launched “Operation Northern Shield” on Tuesday morning to expose and neutralize cross-border Hezbollah tunnels which have infiltrated into northern Israel.While Israeli defense officials have repeatedly denied the existence of cross-border Hezbollah tunnels – despite residents of northern Israel warning of digging sounds underground – the military admitted that it has been aware of Hezbollah efforts to build attack tunnels stretching into Israel at several points along the border since after the Second Lebanon War in 2006.Over the years the IDF received complaints from residents. In 2012, Hezbollah Secretary-General Hassan Nasrallah talked about “Operation Conquering the Galilee,” which would include a component of offensive tunnels that would be designed to infiltrate into northern Israel and attack troops.“Any report by any civilian has been checked in real time with technological and engineering equipment, and the places we’ve examined have been ruled out,” the military said.The following year, the IDF understood that Hezbollah was attempting to begin the construction of the tunnels but that Maj.-Gen. Yair Golan, who was head of the IDF’s Northern Command at the time, told Army Radio that at the time they had “no positive information meaning that there are tunnels. The situation is not similar to what there was around the Gaza Strip.”Nevertheless he added that “this idea of going below ground is not foreign to Lebanon and is not foreign to Hezbollah, so we have to suppose as a working assumption that there are tunnels. These have to be looked for and prepared for.”The same year Golan was quoted as telling a forum that Hezbollah tunnels do not pose a strategic threat on the northern border.The army said on Tuesday that “at that time [in 2013] we could not locate any” tunnels built by Hezbollah, which crossed into Israeli territory.In 2014 after Operation Protective Edge in Gaza, where Hamas used tunnels to enter Israel, the military decided to form a special team in the Northern Command to explore the threat along the border with Lebanon.As was clear to the IDF at the time - that Hamas and Hezbollah were exchanging knowledge, it strengthened the military’s working assumptions that there could be additional threats posed by tunnels in the North as well.In 2015, the Lebanese daily As-Safir published a series of reports detailing Hezbollah’s preparation for war against Israel, which included a sprawling underground network of highly-advanced tunnels housing thousands of rockets ready to be launched.According to the report, the tunnels – which have secondary escape shafts - were built with durable concrete and have a 24-hour power supply via underground generators, as well as a ventilation system to protect military equipment.That same year Israel began to develop technology that would be used to detect tunnels, both on the northern and southern fronts. This technology has helped Israel destroy over a dozen Hamas and Islamic Jihad tunnels from the Gaza Strip as well as those built by Hezbollah, on the northern border.In 2015, Israel also began to invest significant amounts of money and efforts into strengthening its defenses along the border with Lebanon to thwart any ground attack by the terrorist group.In 2016, the IDF began to deploy technological means along the border with Lebanon in order to start locating tunnels built by Hezbollah. Two years later, the IDF announced it had launched Operation Northern Shield.“All of this allowed us this morning to launch an operation based on a good picture we’ve constructed in an effort to expose [Hezbollah’s] project and neutralize it,” the army said on Tuesday, adding that “we’ve been preparing for this operation for two and a half years, with a standing operating procedure personally led by IDF chief of staff Lt.-Gen. Gadi Eisenkot.”The military expects the operation to last several weeks, but stressed that it depends on how Hezbollah responds to the neutralization of their tunnels.