Hamas rocket barrages are reaching deeper into Israel than previous conflicts, but Israel’s military brass is more concerned with the terror group’s newest tactic: commando raids.

Hamas released a graphic video Tuesday, in which fighters from the Izz al-Din al-Qassam Brigades are seen carrying out a tunnel-borne assault on Israeli soldiers at a base in Nahal Oz. The Israeli media also aired a photo of a map containing tunnel routes of future commando attacks.

Since the start of the latest round of fighting in Gaza, Hamas has launched at least six reported incursions into Israeli territory; five by tunnel and another by sea.

With Israel’s development of the Iron Dome anti-rocket system, improved civil defense practices, and a blockade that has forced Hamas to resort to making less potent rockets indigenously, ground incursions could be Hamas’s most effective strategy. Israel’s only way to counter them is to invade Gaza to locate the tunnel entrances and destroy them. This has afforded Hamas the chance to pull the Israeli military into bloody close-quarter battles in the streets of Gaza.

Hamas has also scored a major psychological victory by putting the IDF on the defensive inside Israel. As the Associated Press reported last week, Israeli citizens who were accustomed to sporadic rocket fire have abandoning towns near Gaza, fearing subterranean raids by Hamas fighters.

At least three of the tunnel-borne attacks have resulted in eleven Israeli military casualties and the equipment left behind by militants shows more ambitious intentions, including handcuffs and tranquilizers for kidnapping operations, Israeli uniforms to confuse the IDF, and heavier weapons like rocket propelled grenades and light machine guns for more devastating assaults.

Even Hamas’s failed amphibious raid by five commandos on Zikim on July 8 was cause for Israeli concern. This operation required advanced training, planning, and equipment. With limited resources in Gaza, it was impossible to conduct this without outside help. While Iran was the likely culprit, the training could have come from anywhere.

Israeli tunnel demolitions are expected to be completed in the coming days. This will prevent the threat of commando attacks on Israel in the vicinity of Gaza in the short term. For a longer term solution, the IDF is developing a tunnel detection system which should be operational within a year. As early warning radars have significantly reduced the effectiveness of rocket attacks, this system — if it works — will give security forces time to respond and greatly diminish the threat of Hamas’s subterranean incursions.

Patrick Megahan is a research analyst at Foundation for Defense of Democracies focusing on military affairs. He manages the website militaryedge.org