You're at war with countries X and Y. Does international law say anything about bombing X's embassy in Y (to kill a high-value target)?

Question

Reportedly:

The Iranian ambassador, Hossein Akbari, said Israeli F-35 fighter jets "brutally targeted my place of residence and the consular section of the embassy, along with Iran's military attaches".

[...] the Revolutionary Guards put out a statement saying that seven of its officers were killed, including Brig-Gen Mohammad Reza Zahedi and Brig-Gen Mohammad Hadi Haji-Rahimi, whom it described as commanders and "senior military advisers".

[...] Iranian Foreign Minister Hossein Amir-Abdollahian described the strike as "a violation of all international obligations and conventions" and "blamed the consequences of this action on the Zionist regime", the Iranian foreign ministry said.

So reportedly Israel hit the Iranian embassy in Syria. If some general of country X is in their embassy in country Y, and you're at war with both countries, what international conventions are being violated if you bomb the embassy to smithereens to kill said general?

---

Aside, but for completeness, in the meantime the IDF standpoint was made public:

“According to our intelligence, this is no consulate and this is no embassy,” Israel Defense Forces spokesperson Rear Adm. Daniel Hagari told CNN. [...] “This is a military building of Quds forces disguised as a civilian building in Damascus.”

Anyhow, my question is/was purely based assuming the Iranian framing, as the most interesting question. (Israeli strikes on unassuming buildings in Syria said to house IRGC were more numerous.) Also from that CNN piece, the Syrian reaction (similar to Iran's):

Syrian Foreign Minister Faisal Mekdad meanwhile described the strike as a “gross violation of international regulations, especially the 1961 Vienna Convention on Diplomatic Relations.”

Answer 1

Assuming, for the sake of argument without investigating the issue, that Israel is at war with both Iran and Syria, then the fact that the consulate happens to be in Syria isn't a problem from an international law perspective, and neither is the fact that it is a diplomatic compound. The question would be whether attacking a consulate and consular residence is a permissible target under international law for reasons separate and apart from its diplomatic status. (A New York Times analysis concludes that it doesn't even matter if there is or is not a state of war between Israel and Syria or Iran, and that the only pertinent legal fact is that the embassy or consulate in question is not located in Israel).

In other words, the issue would be whether there is disproportionate harm from the strike to non-combatant civilians who are not legitimate military targets in their own right, to justify the military purpose of attacking the high value target located there.

The international law regarding the laws of war and war crimes does not demand a total absence of collateral damage when attacking a legitimate military target. How much collateral damage is too much, however, is ultimately a judgment call. There is no bright line that distinguishes acceptable collateral damage from too much collateral damage.

As a practical matter, if a military considers the possible collateral damage and weighs it against the military objectives to be achieved in good faith before making the strike, this probably satisfies the striking force's obligations under international law.

Answer 2

If some general of country X is in their embassy in country Y, and you're at war with both countries, what international conventions are being violated if you bomb the embassy to smithereens to kill said general?

China made some detailed statements to this effect after the American bombing of the Chinese embassy in Belgrade in 1999.

The raid caused a dramatic rise in tension between China and the United States. An official statement on Chinese television denounced what it called a "barbaric attack and a gross violation of Chinese sovereignty".[37] China's ambassador to the UN described what he called "NATO's barbarian act" as "a gross violation of the United Nations charter, international law and the norms governing international relations" and "a violation of the Geneva convention".[38] On May 12, 1999, the Legislative Council of Hong Kong passed the "Condemnation of NATO" motion by a rare bipartisan vote of 54-0.[39]

In other words, it has to do with:

• attacking a third nation, i.e., violating its sovereignty (embassies are usually treated as national territory for these purposes)
• attacking diplomatic missions, which are usually immune to military action - even between the belligerents
• attacking non-combatants

More information could be possibly gleaned from this long list of attacks on diplomatic missions.

It seems, that all of the above reasons would still apply to an Israeli attack on an Iranian consulate in Syria, even though Israel entertains diplomatic relationships with neither country.

Realpolitik
However, from the point of view of Realpolitik (or would RealKrieg=realwar be more appropriate?) Iran and its proxies (including Syria) are active belligerents in this conflict (more so than the US and Europe are belligerents in Ukraine), and the assassinated Iranian generals were present there for a reason. This, Israel will probably face formal criticism of the UN, the US, and the European nations, but no consequences. Indeed, the killing of the aid workers probably poses more problems, as the host nations are obliged to demonstrate publicly to their populations that they care about their citizens' lives.

Update
Another similar incident is the attack on a Russian Diplomatic Convoy in Iraq on April 6, 2023:

In Moscow, the Russian Foreign Ministry said it urgently summoned the U.S. and Iraqi ambassadors and asked both to take the necessary measures to guarantee Russian citizens’ safety in Iraq, investigate the circumstances of the attack and punish those responsible.

There is a related Wikipedia article in Russian, but I can't say whether it contains any additional details about the content of the Russian complaints to the ambassador. Surprisingly I couldn't find any mentioning of this incident in English Wikipedia - e.g., see here.

Answer 3

First of all with regards to the specifics of that case. Are these countries actually currently at war? Like the Israel-Syria relations aren't great, they apparently never developed diplomatic relations, but there's limited trade and a ceasefire. While with Iran there are various proxy wars and a difficult relation, but again no outright war, right?

The other thing is that a one sided accusation is not yet a proof of anything.

That being said, if you set aside the actual example and just focus on the situation in the abstract you'd first of all have to check whether these countries have diplomatic relations in the first place.

Usually the development of diplomatic relations comes with erecting embassies in each others country to have a faster and more immediate exchange. And as that comes with a significant risk to these diplomatic staff they usually are granted special protection and immunity. Also if you attack diplomats that is essentially an aggression against official representatives of that state and hence a casus belli or reason to go to war with that country. Not to mention that it puts all your diplomats in grave danger as well.

So if there is no war that's a "great" (read: stupid) way to start one, you'd instead rather end diplomatic relations and ask the other country to leave (and conversely like to be asked to leave the other country as well).

Aside from that there is usually no military gain from attacking embassies, while on the other hand it comes with lots of problems. Like if those countries are well connected and maybe have several embassies in their capital or whatnot so that your attack might not just hit one but several, you might have started war or at least deteriorated relations with several countries and when it eventually comes to negotiating ceasefires and peace, it's somewhat important to guarantee the safety of diplomats as that is the base requirement for having any talks like that to begin with.

So even if you have no diplomatic relations with another country, embassies are still civilian infrastructure and infrastructure that might become valuable later.

That conversely assumes that they are indeed CIVILIAN infrastructure. Though similarly to the obligation of an aggressor to avoid purely civilian infrastructure and excessive civilian casualties, the defendant also has an obligation to not mix military and civilian structures. So if you set up a military head quarter in an embassy, hide weapons and fighters in schools and hospitals and so on, you might make them valid military targets and render the civilians using them collateral damage. So mixing combatants and non-combatants can put the non-combatants in serious danger and can be in itself a war crime. Though that opens up a whole can of worms as to whether the defendant is using human shields or whether the aggressor is targeting civilians or taking creating excessive civilian casualties that serve no military purpose.

Though if there is no diplomatic relation, if the countries are already at war, if there is military purpose in such an attack there's probably. There's likely way less protection to these structures, beyond the regular protection of civilian infrastructure.

Answer 4

It is quite obvious that if Iran would to hit targets inside Israel, that would cause significant increase of already existing sanctions regime against that country, but even more relevant, it would draw universal condemnations from most of the countries.

Therefore, even as these countries for some reason are not ready to put the same amount of pressure on Israel, it nevertheless makes sense for them to condemn such attacks by Israel, as they have the potential of throwing the whole region into major disarray.

It may look like a great proposition to attack the side you do not have peace with, when you assume that side will not return the attack. But what if they eventually do? Then this fragile arrangement will fail and all three countries will plunge into hot war.

So even between countries which are not at peace, international law would prefer to see undeclared truce followed by a cessation of hostilities, rather than sporadic one directional attacks followed by two sided attacks followed by a war.