The United Nations Interim Force in Lebanon (UNIFIL) confirmed on Thursday that a tunnel discovered by Israel earlier this year had crossed the Lebanese-Israeli border, in the third such breach of a ceasefire resolution.

“UNIFIL’s independent assessment confirms that this tunnel crosses the Blue Line in violation of Resolution 1701,” the group said in a statement.

The IDF announced in January that it had found a sixth and final cross-border attack tunnel that the Iranian-sponsored terrorist organization Hezbollah built into Israeli territory. UNIFIL, the United Nations force in charge of keeping the peace on the Lebanese-Israeli border, was informed of the violation.

Five have been confirmed to exist by the UN. “Of these, three tunnels have been found to be crossing the Blue Line,” UNIFIL said on Thursday. The peacekeeping force noted that it had “informed the Lebanese authorities about the violation and has requested urgent follow-up actions.”

The underground infrastructure was described by the IDF as the “longest and most detailed” attack tunnel it had discovered. The tunnel was reportedly 800 meters (2,600 feet) long and extended several meters into Israel. It was also the deepest found to date, at a depth of 55 meters (180 feet).

At the beginning of December, Israel launched Operation Northern Shield to seek and destroy attack tunnels built by Hezbollah, the terrorist group which exercises complete political and military control over Lebanon.

The IDF believes that Hezbollah has built a sophisticated underground structure to allow infiltrators to cross into Israel and to attack border communities. Hezbollah has stated that it intends to attack the Galilee in its next war with Israel and to kidnap or kill Israeli civilians and soldiers.

Hezbollah’s leader, Hassan Nasrallah, dismissed Israel’s success in destroying the attack tunnels. “The uncovering of the tunnels does not affect by 10 percent our plans to take over the Galilee,” he said in January.

[Photo: Israel Defense Forces / Wikimedia Commons]