The Israeli Defense Forces destroyed two underground attack tunnels—one that entered into Israel and another inside central Gaza, said the IDF.

According to IDF spokesperson Lt. Col. Jonathan Conricus, the cross-border terror tunnel was a partially destroyed “old tunnel” built before the 2014’s Operation Protective Edge, which Hamas was trying to rehabilitate by refitting the entrance to Israel onto a newly created tunnel.

The other target eliminated by Israeli fighter jets around midnight on Saturday was a “subterranean complex” in central Gaza and was eradicated in response to last Saturday’s attempted bombing of an IDF convoy patrolling along the Gaza perimeter fence.

“Hamas invested billions in its tunnel project, and now they’re drowning in the sand,” Israeli Defense Minister Avigdor Lieberman said in response to the tunnel eliminations. “I recommend that Hamas invest its money in the welfare of the citizens of Gaza because by the end of the year, its tunnel project will be destroyed.”

He credited the mission’s successes to “high-quality intelligence and breakthrough technology.”

Israel has placed a major emphasis on eliminating the threat of terror tunnels from Gaza, destroying four cross-border tunnels since Oct. 30—three belonging to Hamas and one to Iranian-backed Palestinian Islamic Jihad.

Last year, Israel began construction of a new below-ground wall to end the threat of attack tunnels from Gaza.