Israel's military operation in Gaza has killed tens of thousands of people, destroyed thousands of buildings, and severely restricted the supply of food.
The operation was launched after Hamas rampaged through villages, military posts and a music festival in Israel on 7 October 2023, killing about 1,200 people and taking 251 others hostage. The United Nations' (UN) human rights body would later conclude that Hamas had committed war crimes and crimes against humanity.
Prime Minister Benjamin Netanyahu said at the time that like every country, Israel has an inherent right to defend itself. He argues his country's military operation in Gaza is a just war with the goals of destroying Hamas and bringing home all the hostages.
In January 2024, he said that Israel's commitment to international law is unwavering. That commitment is coming under ever-increasing scrutiny.
Leading human rights organisations and some countries accuse Israel of ethnic cleansing and acts of genocide. Netanyahu denies this and has strongly criticised such allegations.
An important aspect of how international law applies to wars is the principle of proportionality.
In the words of the International Committee of the Red Cross, it means that the effects of the means and methods of warfare used must not be disproportionate to the military advantage sought.
BBC Verify has spoken to a range of international law experts to ask whether they consider Israel's actions to have been proportionate.
The vast majority of them, with different degrees of certainty, told us that Israel's actions are not proportionate. In drawing that conclusion, some reference Israel's conduct of the whole war, some focus on events in recent months.
I would struggle to see how Israel's military conduct in Gaza could potentially be characterised as proportionate, says Prof Janina Dill from the Blavatnik School of Government, University of Oxford.
Dr Maria Varaki, from Kings College London, told us that it is undisputable, non-disputable, actually, that the use of force in Gaza has been disproportionate.
Prof Yuval Shany, at the Hebrew University of Jerusalem, states: The military campaign can no longer be seen as proportionate.
And Prof Asa Kasher of Tel Aviv University, who was the lead author of the IDF's first code of ethics, told us the number of non-combatants killed seems too high to be taken to result from reasonable proportionality considerations.
International law is made up of a series of agreements that most countries in the world have signed. The agreements detail what states can and can't do. They include the UN Charter and the Geneva Conventions, both of which Israel is party to and both of which are relevant to proportionality.
International law is not set out in one place, nor is it governed by a central authority. As we will see, its meaning and application are open to considerable debate.
Regarding proportionality, international law addresses this in two distinct ways.
Firstly, when a state has the right to self-defence, the overall military response must be proportionate to the threat being responded to.
In addition, if at any point during the military operation, it ceases to be necessary and proportionate, the right to self-defence no longer applies.
For example, some argue, such has been Israel's success in weakening Hamas, the military operation is no longer proportionate to the threat that Hamas currently poses. This, I should emphasise, is contested.
The second way international law addresses proportionality concerns each individual military action within a conflict, such as an air strike.
The expected harm to civilians or civilian buildings must be proportionate to the expected military advantage gained from that particular action.
Intent is a vital consideration here. What civilian harm is anticipated? And is the expected military advantage proportionate to this?
It is important to emphasise that intentionally harming civilians is always a breach of international law. Proportionality is not a consideration if this is done.
Also, while international law does allow for circumstances in which civilians are killed during the course of a military action, there is always an obligation to minimise civilian harm wherever possible.
Both areas of law are clear: whatever the provocation or the threat, there are rules and limits on what can be done - in the overall response and individual actions. They must be proportionate.
Let's begin with the impact of Israel's overall operation.
More than 64,500 people have been killed by Israel during its campaign - almost half of them women and children, according to Gaza's Hamas-run Ministry of Health. The ministry's figures do not distinguish between combatants and civilians.
Israel has challenged the accuracy of the ministry's figures, both the overall number and the demographic breakdown, but they are quoted by the UN and others as the most reliable source of statistics on casualties available.
UN Secretary General António Guterres recently declared the levels of death and destruction in Gaza are without parallel in recent times.
At the start of the year, the Israeli military said it had killed about 20,000 Hamas operatives, although it has not provided evidence, and does not allow foreign media, including BBC News, free access to Gaza. The Israel Defense Forces (IDF) has not provided any figures for civilian casualties.
The IDF told us that it is committed to mitigating civilian harm during operational activity and that it makes great efforts to estimate and consider potential civilian collateral damage in its strikes.
Israel also accuses Hamas - which is proscribed as a terrorist organisation by the UK, Israel and others - of causing casualties by operating within civilian areas.
It has released numerous videos of what it says are Hamas tunnels running under civilian buildings, including hospitals. Israel says Hamas uses these underground networks to plan and organise attacks. Some of the freed hostages have also described being held in tunnels.
Prof Nicholas Rostow, former legal adviser to the US National Security Council under President Ronald Reagan and a distinguished research fellow of the National Defense University, argues that Hamas used hospitals, schools... as a base of military operations, putting civilians at risk. That was their intention.
Because of this, Prof Rostow says he is not prepared to say that Israel has acted disproportionately. He says he knows how the IDF operates and that it bend[s] over backwards to respect the laws of war.
But even if that is the case, Israel has still killed tens of thousands of people.
Dr Nimer Sultany, editor-in-chief of The Palestine Yearbook of International Law and chair of the Centre for Palestine Studies at SOAS University of London, is categorical. Israel's campaign has been disproportionate since October 2023, because of the unprecedented civilian harm it caused in Gaza, he told us.
Gerry Simpson, professor of public international law at the London School of Economics (LSE), told us, referencing the number of people killed and other consequences for Gaza, that: It is hard to seriously argue that the campaign has been conducted with due regard to the general principles of proportionality and distinction at the heart of the laws of war.
The impact on a population's living conditions is another factor in assessing the proportionality of Israel's overall response.
Israel's restricting of goods into Gaza is not new. This was happening before 7 October and increased after the attack.
Then, in early March this year, Israel began a total blockade of aid into Gaza. It said it was doing so to stop Hamas stealing supplies and using them to finance its terror machine. Hamas denies doing this.
The blockade was condemned by the UN and many countries.
Senior UN officials accused Israel of using food as a weapon of war, which is a crime under international law. Such actions cannot be proportionate.
You can never use starvation of either enemy fighters or the civilian population, says Prof Mary Ellen O'Connell, of the University of Notre Dame in Indiana. You must permit the entry of humanitarian assistance to the civilian population. That is a principle of customary international law. You cannot use starvation. There are certain weapons you can never use.
Benjamin Netanyahu denies this is a weapon that Israel is using.
The UN also accused Israel of deliberately and unashamedly imposing inhumane conditions on civilians. Israel denies doing this too.
A quarter of Palestinians in Gaza are suffering from famine, according to the UN-backed global hunger monitor.
In May, Israel partially eased the aid blockade and introduced a new system of food distribution operated by a US and Israel-backed group called the Gaza Humanitarian Foundation (GHF).
More than 200 charities and other NGOs have called for the GHF to be shut down, claiming Israeli forces and armed groups routinely open fire on those seeking aid.
The United Nations says more than 2,000 people have been killed around aid sites and convoys in recent months. In August, it said most of the killings were by the Israeli military. Israel denies this.
Israel says the GHF's system provides direct assistance to people who need it, bypassing Hamas interference.
But many people who need assistance are not receiving it.
Israel's Ministry of Foreign Affairs called a recent assessment of a quarter of the population suffering famine a tailor-made fabricated report to fit Hamas's fake campaign. The IPC has issued a response defending its methodology.
Aid agencies, senior UN officials, the UK government and others all say the famine and starvation in Gaza are a result of Israel's actions.
Netanyahu says that any food shortages are the fault of aid agencies and Hamas. Also, despite the mounting evidence, he has repeatedly denied that starvation is taking place.
Civilian harm caused by the overall operation also includes the damage or destruction of buildings.
In May, Israel's far-right finance minister, Bezalel Smotrich, declared that Gaza will be entirely destroyed. That is getting closer.
The latest UN estimate is that up to 42% of buildings in the Gaza Strip have been destroyed and 37% damaged.
Prof Emily Crawford, who teaches international humanitarian law at the University of Sydney Law School, told us the complete destruction of infrastructure necessary for the survival of the civilian population... is clearly disproportionate.
Israel's Defence Minister Israel Katz looked ahead to an assault on Gaza City, posting on social media he demanded that Hamas frees the hostages and disarm: If they do not agree, Gaza, the capital of Hamas, will become Rafah and Beit Hanoun.
These are both cities that Israel has reduced to ruins.
As well as destroying and damaging buildings during its offensives, BBC Verify analysis suggests Israel has also systematically destroyed buildings in areas it controls.
The IDF said the destruction of property is only performed when an imperative military necessity is demanded. To Israel the overall military necessity of its operation is not just the severe weakening of Hamas, but its complete defeat.
Former UK Supreme Court Justice Lord Sumption wrote in a recent article: The destruction of Hamas is probably unachievable by any amount of violence, but it is certainly unachievable without a grossly disproportionate effect on human life.
Israel insists it adheres to international law and applies it correctly. BBC Verify asked Israel's government for the legal advice, or a summary of it, that supports its view that its overall military response to 7 October has been proportionate. We did not receive a reply.
In late 2024, judges at the International Criminal Court (ICC) issued an arrest warrant for Netanyahu, saying there were reasonable grounds to believe he bore criminal responsibility for alleged war crimes and crimes against humanity in the Gaza war.
The vast majority of the experts we spoke to believe that all or some aspect of Israel's actions have not been proportionate, in particular with regards to its overall operation. They reach that conclusion for different reasons and with differing degrees of certainty.
Prof O'Connell, of Notre Dame University, told us: There are rules, and they're not being complied with.
Prof Yuval Shany, from the Hebrew University of Jerusalem, says there is an argument that Israel's actions were initially proportionate but there seems to have been, however, a point crossed at which Hamas has been weakened to such a degree that the continuation of the military campaign can no longer be seen as proportionate in nature, given its extensive scope, scale and consequences.
Sadly, the conflict continues with a much-diminished Hamas still fighting, still holding hostages and still denying Israel's right to exist.
