Conflict between Israel and Hamas is underway again. Naturally the accompanying war of words has also flared up. Technical legal terms under the Laws of War are being fired by these rhetorical warriors at each other as frequently as the actual rockets and bullets are being exchanged by the warring parties. “Genocide” “Massacre” “War Crime” “Human Shields” “Disproportionate Response.”

These loaded words are thrown around without any actual understanding of their meaning. Since Operation Protective Edge is a war of words as much as a war of weapons, therefore the meaning of these legal terms must be stated and clarified; that is, if Israel has any interest in winning the war for minds in addition to the war on the battlefield.

The most common gripe thrown around is that Israel’s response to Hamas is “disproportionate.” We’re hearing it now, we heard it in 2012 during Operation Pillar of Cloud, and in 2009 with Operation Cast Lead. As a rule of thumb, those pundits and media analysts complaining about proportionality generally don’t have the slightest clue as to its true meaning.

There are two types of proportionality: Proportionality under jus ad bellum (legality of going to war) and Proportionality under jus in bello (how to act within the confines of international law while at war).

Jus ad bellum Proportionality determines the permissible intensity and magnitude of the proposed military action, stipulating that the force used against another side must be proportional to the attack suffered. The ICRC clarifies this by stating that proportionality’s aim is to establish whether “the means employed are appropriate in relation to the aim sought by the response…a proportionate response…is [one] necessary and appropriate to repel the attack which entails acceptable side-effects on other interests and values affected by the response…[qualitative proportionality’s] aim is…to give the attacked state…the right to repel the attack, using the means appropriate to the particular circumstances.” Former ICJ judge Rosalyn Higgins has said that proportionality must be judged in relation to the overall legitimate objective of ending a prior aggression and, “may mean that a use of force [can be] more severe…than any single prior incident might have warranted.”

Jus in bello Proportionality is governed by Article 51(5)(b) of Additional Protocol I of the Geneva Conventions, which states that an armed attack is indiscriminate, and therefore violative of proportionality, only if it is expected to cause incidental loss of civilian life, damage to civilian property, or both, that is in excess of the anticipated military advantage to be gained from the attack. Article 8(2)(b)(iv) of the Statute of the International Criminal Court explains that this prohibits, “intentionally launching an attack in the knowledge that such attack will cause incidental loss of life or injury to civilians or damage to civilian objects … which would be clearly excessive in relation to the concrete and direct overall military advantage anticipated.” This is often tricky, as the ICRC itself admits, “Application of…proportionality is more easily stated than applied in practice…the law is not clear as to the degree of care required of the attacker…” Professor Leslie C. Green states that the calculus is “subjective,” but must be made in “good faith.” The standard, however, is “the contribution to the military purpose of…the operation as a whole, as compared with other consequences of the action, such as the effect upon civilians…”

All of that legalese essentially means that the methods you use in going to war have to be only those necessary to stop the threat that caused you to go to war to begin with; and once you are at war, the inevitable and regrettable civilian casualties that will occur in individual strikes and attacks can’t be more than the military advantage you expect to gain, overall, from the attack.

So, the measuring stick of a war being “disproportionate” is not a tit-for-tat analysis. The Laws of War do not obligate Israel to employ only the lightest means available at its disposal against a militarily weaker enemy. That would be absurd. Nations go to war to end the armed threat posed by another side; in other words, they go to war to win. Professor Michael Schmitt highlights this by stating that “Proportionality does not require any equivalency between the attacker’s actions and the defender’s response. Such a requirement would eviscerate the right of self-defence.”

The popular interpretation peddled by amateur jurists would essentially forbid a nation from winning a war, basically obligating Israel to end its war with Hamas in a tie. This parity is not demanded by law and a nation is allowed to win its wars since, by definition, wars are only won by applying more force than the enemy can muster, and international law still recognizes that fact.  How much force is proportional? Schmitt says, “the determination is an operational one.” If what is required to repel the threat posed is the total decimation of the enemy’s forces, then that is proportionate and therefore permissible.

Hamas poses a lethal threat to an ever-expanding number of Israel’s population. Its rocket arsenal, now augmented by M302s, can now reach, by Hamas’ own admission, “any point in Israel.” This is not a theoretical threat. Hamas is firing these rockets indiscriminately – with the intent to terrorize Israel’s civilian population and kill as many Israelis as its means allow – as far north as Haifa. Against this very real threat, Israel is allowed to employ any and all means necessary to make these rockets stop – and not for a limited time, but permanently.Therefore, if the use of Israel’s heavier military hardware against Hamas is the only way to permanently silence the threat posed by the terrorist organization, even if those means outweigh anything that Hamas can muster, Israel’s armed attack is still within the bounds of proportionality.

Beyond that, no country – and that includes Israel – is required to ensure that its military attacks completely eliminate civilian casualties. Proportionality permits armies to act even with the knowledge that noncombatants will be harmed. In fact, the ICRC says that in modern war the standard ratio of civilian casualties to combatants is 10 civilians killed to each combatant. That means that 90% of all casualties in modern war will be civilians. Israel has admirably tried to reduce that ratio and succeeds more often than not; but advanced military technology should not be confused for magic. Civilian casualties will occur. Jus in bello proportionality only forbids civilian casualties that are “excessive” compared to the anticipated military gain. But “excessive” should not be confused with “extensive.” Professor Yoram Dinstein states that, “Even extensive civilian casualties may be acceptable if they are not excessive in light of the concrete and direct military advantage anticipated.”

To comply with the rules of war, Israel must only ensure that the inevitable civilian casualties will be proportionate to the military advantage it expects to gain from the individual attack. This is an evaluation carried out before each strike. Dinstein states, “Much depends on the factual situation.”  We routinely see Israel call off its air strikes when the determination made that proportionality is not met.

Israel’s security cabinet is now reportedly in the process of discussing a ground invasion of Gaza. Does such a move violate proportionality? If the air and artillery strikes are incapable of ending the very real threat that Hamas poses to Israel’s civilian population, and a ground invasion is the only means to eliminate the threat from Hamas, then sending in thousands of ground troops will still not violate proportionality.

In the end, it would be absurd and unrealistic to legally obligate Israel to fight Hamas to a stalemate. That’s precisely why these periodic flare-ups keep reoccurring, each time leading to tragic and regrettable civilian casualties on both sides. Hamas’ existence and ability to harm Israelis is as detrimental to Palestinian well-being as it is to Israel’s, because it invites the inevitable Israeli military response. One of the oft repeated cliches of this conflict is that no country can accept a situation where rockets are constantly being fired on its civilian population. Israel will not, and should not, accept such a situation, and it will respond militarily. Therefore, it is in the best interest of all sides involved that Hamas’ capability to threaten Israel’s cities and civilians be utterly and permanently destroyed. Not only that, but it’s entirely legal and proportional as well.