Debate on polyurethane foam to seal Gaza tunnels

Foam harder than concrete for sealing tunnels

The debate highlights a high-density polyurethane foam system designed to block the underground tunnel network in Gaza. The material expands upon application and hardens to exceed concrete's strength, intended for injection into known access points and vents to hinder combatant movement and arms transport. Discussions on its efficacy have led to proposals for alternatives ranging from pressurized water to gas injection and sewage use, a technique reportedly employed by Egypt in the past to flood cross-border tunnels.

What is polyurethane foam and how it works

Polyurethane foam is a polymer that expands when its components mix and hardens within minutes. Applied in large quantities, it can fill galleries and permanently block passage. In the context of Gaza's tunnels, this allows sealing sections without deploying troops in hostile environments, reducing casualty risks. Described as harder than cement once cured, it creates a plug difficult to remove without heavy machinery.

The main advantage is remote operation: injected from the surface or tunnel entrances, it expands inward. This avoids close-quarters combat where technological superiority diminishes. However, effectiveness relies on precise knowledge of the subterranean network, estimated to be far more extensive than mapped.

Alternatives on the table: water, gases, and sewage

Foam is not the only option discussed. Some analyses suggest using pressurized water, leveraging proximity to the sea, to flood tunnels and force occupants out. Others propose injecting gases denser than air, such as carbon dioxide, to displace oxygen and cause asphyxiation, though handling poses risks to the civilian population above ground.

A third approach, reportedly already used, involves sewage. Egypt allegedly flooded cross-border tunnels with wastewater to curb smuggling. This is presented as a low-cost, highly available option, although its large-scale efficacy remains unquantified.

Debate on civilians and responsibility

These techniques have reignited controversy over civilian presence in operational zones. Some argue tunnels are exclusively military, occupied by combatants or collaborators, implying no innocent victims. Others contend the network also shelters families, warning that blocking ventilation could prove lethal for non-combatants.

The discussion shifts to infrastructure funding sources. It is claimed that international humanitarian aid funds were diverted to tunnel construction, causing grievance among donors who believe their contributions financed war rather than improving living conditions.

Historical context and future warnings

Opinions reference Israel's 2006 withdrawal from Gaza and Hamas's subsequent takeover. The lack of elections in the West Bank since then is attributed to Fatah's antiestéticar of a Hamas victory. A cited poll suggests 67% of Gazans support attacks on Israeli civilians, arguments used to claim the disconnect between population and authorities is smaller than assumed.

Warnings note that conflict will not end with tunnel destruction. Attacks are predicted to resume after months or years because root causes remain intact. The debate concludes without consensus on whether tunnel blocking is proportionate or collective punishment.

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Key Facts

• Polyurethane foam expands and hardens to surpass concrete's strength.
• Egypt reportedly flooded cross-border tunnels with sewage since 2013.
• A cited poll indicates 67% of Gazans support attacks on Israeli civilians.
• Israel withdrew from Gaza in 2006.

Large-scale foam efficacy lacks public data verification. The number of operational versus sealed tunnels remains unclear. What seems certain is that debates on methods and civilian consequences will persist beyond the final blocked tunnel.