Source: Indian Express  

Introduction 

The recent Israeli airstrikes on Iranian military and nuclear facilities have reignited critical debates about the boundaries of international law and the doctrine of preemptive self-defense. As tensions escalate between these regional powers, legal experts remain divided on whether Israel's actions constitute legitimate self-defense or illegal preemptive strikes. The question extends beyond bilateral relations, potentially implicating U.S. involvement and challenging the foundational principles that govern when nations can justifiably use force against each other. 

What is Jus ad Bellum? 

•  Jus ad Bellum, literally meaning "right to war," represents the body of international law that determines when states may legitimately resort to armed forces.  
• This legal doctrine, enshrined in the UN Charter, establishes that military force is prohibited except in two circumstances: self-defense against armed attack or authorization by the UN Security Council. 
• The principle traces back to the 1837 Caroline test, which established that preemptive self-defense is only permissible when facing an "imminent, overwhelming threat" that leaves no alternative but immediate military action. 

How Have Iran-Israel Relations Evolved from Strategic Alliance to Shadow War Since 1948? 

Pre-1979 Alliance Era: 

• Iran was among the first Middle Eastern nations to recognize Israel's statehood in 1948. 
• Under Shah Mohammad Reza Pahlavi's pro-Western regime, Iran and Israel enjoyed robust diplomatic and strategic relations. 
• Iran pursued David Ben Gurion's "periphery doctrine," forming alliances with non-Arab Muslim nations to counter Arab hostility. 
• Despite economic boycotts from Arab states, Iran maintained oil trade with Israel and established significant diplomatic cooperation. 

Revolutionary Transformation (1979): 

• The Islamic Revolution fundamentally altered Iran-Israel relations. 
• Ayatollah Khomeini's theocratic regime rejected Israel's legitimacy, branding it the "Little Satan" alongside the US as the "Great Satan". 
• Iran's new Islamic government viewed Israel as a colonial occupier of Palestinian lands. 

Shadow War Period: 

• Despite severed diplomatic ties, Israel secretly supported Iran during the Iran-Iraq War (1980-1988) to weaken Iraq's regional power. 
• This tactical cooperation evolved into sustained proxy warfare. 
• Iran began funding and arming militant groups like Hezbollah in Lebanon and Hamas in Gaza. 

Israel responded with targeted assassinations of Iranian nuclear scientists and cyberattacks like the Stuxnet virus against Iran's nuclear facilities. 

Does Israel’s Recent Strike on Iran Violate the Principle of Imminent Threat Under International Law? 

• International law fundamentally prohibits states from using force against each other, except in cases of self-defense or UN Security Council authorization. 
• The Caroline test, dating back to 1837, establishes that force can only be used when "absolutely necessary" to address an "imminent, overwhelming threat." 
• Israeli Prime Minister characterization of the strikes as preventing Iran from materializing nuclear capabilities "within a few months" raises questions about whether this meets the imminence standard.  
• Legal scholars like Marko Milanovic argue there's no credible evidence of an imminent Iranian nuclear attack, suggesting Israel's actions may vi main headin golate this centuries-old principle. 

Does Israel’s Recent Strike on Iran Violate the Principle of Imminent Threat Under International Law? 

• Some legal experts contend that Israel's strikes represent a continuation of legitimate self-defense against Iran's proxy network, including Hamas, Hezbollah, and Houthi rebels.  
• This argument hinges on the "Nicaragua test," which determines when a state can be held responsible for proxy actions through "effective control" or "substantial involvement."  
• While Iran maintains significant influence over groups like Hezbollah, evidence suggests these proxies often act independently—Hamas reportedly failed to secure Iranian backing for the 7th October, 2023 attacks.  
• The ongoing Houthi attacks on Israeli territory and Red Sea shipping, however, may provide stronger grounds for linking Iran to continued aggression. 

Does Israel’s Military Response to Iran Meet the International Law Standards of Necessity and Proportionality? 

• Even if Israel's actions qualify as legitimate self-defense, international law requires that military responses be both necessary and proportional to the defensive need. 
• The scope of Israel's bombing campaign against Iranian nuclear and military facilities must be evaluated against the actual threat posed and available alternatives.  
• Previous direct exchanges between Iran and Israel in April and October 2024 were relatively limited, raising questions about whether the current escalation maintains proportionality or represents an excessive response that could further destabilize regional security. 

Would U.S. Military Support for Israel Against Iran Be Legal Under International Law? 

• The potential for U.S. military intervention adds another layer of legal complexity, as President Trump considers strikes against Iran's Fordo nuclear facility. 
•  International law permits collective self-defense when assisting victims of unlawful attacks, provided the victim state requests help.  
• However, if Israel's actions are deemed illegal under international law, then U.S. participation would likely be illegal as well, unless America can establish an independent justification for self-defense against Iran.  
• This interconnection highlights how violations of international law can cascade, potentially drawing multiple nations into legally questionable military actions. 

Conclusion 

The Israeli-Iranian conflict represents more than a regional dispute—it's a test case for the international legal order that has governed state behavior for centuries. Whether Israel's strikes constitute legitimate preemptive self-defense or illegal aggression will likely never be definitively resolved in international courts, but the precedent being set matters enormously. Each violation of established legal norms weakens the shared expectations that help maintain global stability, making the world incrementally more dangerous and unpredictable for all nations.