ISTANBUL

International organizations have conveyed worries regarding the expansion of the conflict between Israel and Hamas and the potential introduction of chemical weapons.

Recent news reports claim that Israel, supported by the US, could flood Hamas tunnels with nerve gas and chemical weapons as Tel Aviv prepares for a ground invasion of the besieged Palestinian territory.

Israel has also been using white phosphorus bombs against the Gaza Strip -- confirmed by international rights groups such as Human Rights Watch and Amnesty International.

All of that raises the question of the legality and legal status of chemical or biological weapons.

Here is what international law says and what, if any, could be the repercussions for one that uses the weapons in warfare.

What are chemical weapons?

Chemical weapons are substances that consist of toxic chemicals employed with the deliberate intention to cause harm, incapacitate or cause fatalities among human populations in the context of armed conflict.

The substances encompass a diverse range of chemical agents, including but not limited to nerve agents, blister agents, blood agents, choking agents and incapacitating agents.

They can exist in various physical forms, such as gases, liquids or solids, and are engineered to inflict harm by penetrating the body's physiological systems -- primarily the respiratory and nervous systems.

White phosphorus is a highly flammable and toxic substance that creates smokescreens and burns at temperatures high enough to melt metals.

It can burn human skin down to the bone and cause severe respiratory damage and organ failure.

But its use is not explicitly prohibited under international law due to legal loopholes, which allow militaries to categorize it as not being an “incendiary weapon,” which is banned under Protocol III of the 1980 Convention on Certain Conventional Weapons.

Where have chemical weapons been used?

The use of chemical weapons became widespread during World War I, with countries deploying lethal gases, including chlorine, phosgene and mustard gas.

The international repercussions arose due to the violation of the Hague Conventions of 1899 and 1907, which explicitly prohibited the use of "poison or poisoned weapons" in warfare, leading to diplomatic protests including warring countries. However, it was limited.

WWI gave rise to the development of such international agreements and treaties as the 1925 Geneva Convention. The convention prohibited the use of chemical and biological weapons in warfare but did not specify their production and stockpiling.

Chemical weapons were also used during WWII, such as mustard gas and nerve agents, which accelerated the development of international efforts to ban their use.

The Nuremberg Trials held after World War II established that the use of chemical weapons constituted a war crime, leading to convictions for individuals involved in their deployment.

During the Cold War, the US and the Soviet Union produced and stockpiled chemical weapons in great amounts, raising international concerns about possible usage.

What does international law say about chemical weapons?

The main international law on the munitions is the Chemical Weapons Convention, officially known as the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction.

It was drafted in 1992 and took effect in 1997.

The CWC banned the production, stockpiling and use of chemical weapons, and currently has 193 signatories.

Israel has signed but not ratified the agreement, which means that it is not legally obliged to adhere to the CWC.

The Convention defines chemical weapons as: “Toxic chemicals and their precursors, except where intended for purposes not prohibited under this Convention, as long as the types and quantities are consistent with such purposes.”

Under any violation, the CWC established the Organization for the Prohibition of Chemical Weapons (OPCW) to oversee compliance, which can lead to sanctions, including diplomatic isolation, and referral to the United Nations Security Council for further action.

The Syrian Civil War witnessed alleged chemical attacks, such as the most notable in the 2013 Ghouta chemical attack.

It led to harsh reactions from international actors and as a result of pressure, Syria joined the CWC in 2013.

As a condition of joining the CWC, Syria declared its chemical weapons stockpile and agreed to the destruction and removal of the weapons under the supervision of the OPCW.

The Halabja massacre in 1998 by Iraq’s Saddam Hussein regime used chemical weapons against Kurdish civilians, resulting in thousands of deaths.

Another example of the use of chemical attacks is the Houthi rebel attacks in Yemen, which have been accused of using chemical weapons, including chlorine gas.

Chemical weapons are 'weapons of mass destruction’

From contaminating water supplies during medieval sieges to the poisoning of bullets in the 17th century, the contentious issue of chemical weapons gained prominence during WWI because of the deployment of chlorine gas in 1915 and eventually the development of other toxic gases like phosgene and mustard gas, according to Ali Oguz Dirioz, an international relations expert in the Turkish capital of Ankara.

But the issue was “not on the agenda until the 1874 attempted agreement about the Brussels Convention prohibiting poisonous weapons (which never entered into force),” Dirioz told Anadolu.

Chemical weapons are labeled as "weapons of mass destruction" (WMDs) because they can harm civilians, women, children, combatants and even non-combatants like aid workers indiscriminately, he said.

Emphasizing the protection of civilians, Dirioz said international conventions focus on the use of conventional weapons rather than WMDs, which can “indiscriminately” harm combatants and non-combatants, regardless of their affiliation.

Such mechanisms like CWC and OPCW “are similar to the role of the International Atomic Energy Agency in implementing inspection mechanisms to apply the Non-Proliferation Treaty, which aims to prevent the proliferation (spreading) of nuclear weapons,” he said.

Regarding the gas agents that are used in chemical weapons, he said that although many gas agents are categorized as chemical weapons -- napalm, which was initially not included in the list, was used by the US in the Vietnam War but later banned by the UN Convention on Certain Conventional Weapons in 1980.

He said white phosphorus bombs “are also part of the CCW and their use against civilians is prohibited.”

“Chemical weapons use is not permitted and is against international law,” added Dirioz.