There are more complications. Lebanon is a sovereign state, but Israel says it is fighting Hezbollah, which is both a militant group and an influential player in Lebanon’s government. (Israel, the United States and Australia consider it a terrorist organisation.)
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Israel has been in violent conflict with Hezbollah since the group was founded in the 1980s, with help from Iran, to fight Israel’s occupation of Lebanon.
Most recently, after Hamas led the October 7 terrorist attacks, Hezbollah began firing rockets and missiles at Israel in solidarity with Hamas. Israel returned fire, and the two sides carried out nearly a year of exchanges. Civilians and combatants in Israel and Lebanon were killed, and more than 150,000 people displaced on both sides of the border.
Some experts say the invasion is legal because Lebanon allows Hezbollah to use its territory to strike Israel.
In light of the Hezbollah rocket and missile attacks, “Israel has the legal right to take self-defence measures against Hezbollah, and probably also against the Lebanese state,” Amichai Cohen and Yuval Shany, two Israeli law professors, wrote in an essay published for the Lieber Institute for Law and Warfare.
In an email, Shany said the United States and its allies had used similar reasoning to “operate in Syria against ISIS and in a number of other countries who had al-Qaida presence”.
“As we note in our piece,” he added, “the case for self-defence in Lebanon is even stronger.”
Humanitarian legal protections
Separate from questions about the legality of Israel’s invasion, every country has a legal obligation to safeguard civilians during warfare.
Even if Hezbollah places military targets in civilian buildings, experts say Israel must consider the safety of the noncombatants inside when it conducts airstrikes. (International law does not distinguish between ground invasions and airstrikes — the measure is “use of force,” according to Oona Hathaway, a professor of international law at Yale University.)
The United Nations says more than 1,500 people have been killed in Lebanon by the Israeli military in the past two weeks, including hundreds of deaths in a single day in September, during one of the most intense air raids in recent warfare.
Enforcing the law
It is difficult, if not impossible, to enforce international laws of war when nations disagree on how, or even whether, to act against violations.
The International Court of Justice allows lawsuits to be brought against states accused of violating treaties, such as the genocide charges South Africa has lodged over Israel’s military operations in Gaza.
Were a case to be referred to the international court over Israel’s military operations in Lebanon, Ambos said, Israel could refuse to comply with the outcome. That could send the dispute to the Security Council to be enforced.
The UN General Assembly could also be asked to seek a resolution, Hathaway said. But it does not have the authority to take action against Israel except to call on member states to do so.
“The question is, who will enforce this?” Ambos said.
This article originally appeared in The New York Times.
