Is a buffer zone — such as the one that Israel is establishing in Lebanon — legal under international law?
The short answer is: possibly.
But the long answer is more complicated and, experts say, leads to the conclusion that what Israel is establishing in southern Lebanon may not actually be a “security buffer zone” at all, at least not under international law.
Since early March, Israeli troops have taken over an area of Lebanon between 5 and 10 kilometers (3–6 miles) from the border. Israel says it is acting in self‑defense. Prime Minister Benjamin Netanyahu says the buffer zone in southern Lebanon is meant to “thwart the threat of invasion” from the Lebanese militant group Hezbollah.
Why the legality question is complicated
Buffer zones as used in modern warfare and politics are not well defined under international humanitarian law. Much of that law was developed after the world wars and the standard sources — the UN Charter, the Geneva and Hague Conventions — do not explicitly address buffer zones.
Gustav Meibauer, an assistant professor in international relations at Radboud University, notes that buffer zones are not explicitly covered anywhere in international law. Legal researcher Eian Katz, in a widely cited 2017 University of Chicago Law Review article, argues buffer zones can have legitimate uses: enhancing border integrity, guarding against threats from nonstate actors, containing war zones, sheltering displaced people, or enabling aid distribution. But Katz also warns they can be used as a pretext to expand influence or pursue foreign policy objectives.
Meibauer adds that the legal gray zone can make buffer zones politically attractive. Decision-makers may prefer the softer label “buffer zone” over terms like occupation or annexation, which carry stronger legal and political connotations.
Reasons and legal tests for buffer zones
Several factors matter when deciding whether a buffer zone is legal. A key distinction is whether it was created by mutual agreement or imposed unilaterally. Mutually agreed zones between states — for example to avoid accidental clashes — are generally unproblematic under international law. Unilateral imposition on another country, however, can threaten sovereignty.
When a buffer zone is imposed without agreement, three overlapping arguments are typically offered to justify it:
– It was permitted by the UN Security Council.
– It is being established for humanitarian reasons.
– The imposing state is acting in self‑defense.
How buffer zones must operate under law
Even if a buffer zone is established, international law governs its operation. The Geneva Conventions and their Additional Protocol provide the basic rules for armed conflict, including the principles of proportionality and military necessity. These principles require any use of force to be necessary to achieve a legitimate military objective and proportionate in relation to the expected military advantage.
The conventions also protect civilian objects, private property and infrastructure: they should not be targeted or destroyed except in strictly defined circumstances when they contribute to a military objective. Janina Dill, co‑director at Oxford University’s Institute for Ethics, Law and Armed Conflict, has said deliberate, widespread destruction of civilian property without clear military necessity amounts to a war crime.
The same standards apply to conduct against people in a buffer zone. Where feasible, forces should attempt contact, identification and diversion before using lethal force against civilians. Nevertheless, illegal uses of force have become common in many buffer zones.
What has happened in southern Lebanon
Israel has claimed Hezbollah is using buildings in the area it controls. In March, Israel’s defense minister ordered the military to “accelerate the destruction of Lebanese homes” near the border, describing the approach as modeled on tactics used in Gaza. Verification teams have reported extensive destruction: by mid‑April, more than 1,400 buildings in the Lebanese buffer zone had reportedly been destroyed since early March. Around 1 million Lebanese civilians have been displaced.
Permanence and the risk of occupation
Another legal factor is permanence. Early international law viewed buffer zones as temporary; when hostilities end, the need for them usually ends. If a buffer zone becomes a de facto permanent arrangement — territory rendered uninhabitable and under the effective control of a foreign power without the host state’s consent — it may amount to occupation.
Under international law, an area is occupied when foreign forces are in place without the consent of the sovereign state and have established effective control. Occupation triggers extensive legal consequences governed by the Geneva and Hague Conventions.
Political statements and intent
Official statements about intent matter politically if not legally. Some US and Israeli officials have debated whether Israel intends to hold territory in Lebanon permanently. US Secretary of State comments suggested Israel does not want to hold Lebanese territory permanently, while senior Israeli politicians, including the defense minister, have at times suggested otherwise and told displaced civilians they would not be allowed to return to their homes.
Conclusion
Because buffer zones sit in a legal gray area, legality depends on how a zone was created, the reasons given for it, how it is operated in practice, and whether it becomes a permanent arrangement that amounts to occupation. Even where a buffer zone is justified, the operation of forces within it must comply with the Geneva Conventions’ rules on proportionality, necessity and protection of civilians. If those rules are violated — for example through widespread destruction of civilian property without military necessity or unlawful use of force against civilians — the conduct may constitute war crimes or other breaches of international humanitarian law.
Edited by: Rob Mudge