Since the beginning of May 2019, violence has increased between Israel and militants in Gaza. Significant media and legal attention has focused on Israel’s response to rocket attacks fired from Gaza: The Israeli government has attacked militants directly, attacked a Hamas cyber facility and limited fishing rights in the Gaza fishing zone. Along with rocket attacks, however, Israel has also been subjected to frequent attacks by incendiary balloons. By early June of this year, these attacks had destroyed approximately 4,300 acres of land, and more has been destroyed since then. Yet news reports on the incendiary balloons often fail to identify the balloons for what they are—a war crime.

Traveling in Israel recently with a group of national security lawyers from government and private practice, I witnessed and documented some of these incendiary balloon attacks firsthand. (I was traveling in my personal capacity on a trip organized by the Foundation for the Defense of Democracies, a Washington, D.C.-based think tank.) The attacks I saw amount to war crimes under international humanitarian law (IHL).

On June 27, our group was visiting Kibbutz Kfar Aza—an area near Gaza but part of Israel since the country’s independence in 1948. The communities that lie within a few miles of Gaza, referred to as the Gaza Envelope, are routinely attacked with rockets and mortars from terrorist and militant groups inside Gaza. A resident of the kibbutz showed us numerous exploded rockets and mortars that she recovered from her yard and community. She also showed us a fire balloon she recovered earlier that morning along with the note attached, both pictured below.

These fire balloons are cheap, simple to mass produce, and effective in their design and destructiveness. They consist of a bomblet made of a small bag holding an accelerant-soaked roll of gauze (or other absorbent material), connected to a homemade fuse and tied with a string to a balloon (in this case, a condom, used as a balloon). The natural and constant breeze off the Mediterranean Sea, which blows from Gaza to Israel, carries these incendiary devices into the civilian communities in Israel, some just a few hundred meters (or less) away from the border with Gaza. The fuse eventually burns the string that connects the bomblet to the balloon, dropping the bag and remainder of the fuse to start a fire wherever it lands. Not all the fuses stay lit, and sometimes the balloons deflate or get caught in trees. Sometimes they land harmlessly on concrete, but at other times they damage or destroy buildings or acres of farmland, and they can require significant resources to extinguish. This particular device was recovered a few hours prior to our group’s arrival to Kfar Aza.

After we left Kfar Aza and went to our next stop, overlooking Gaza City, we witnessed numerous fires in the fields around us caused by these incendiary balloons. We were standing on charred earth, burned a few days prior by similar devices. The pictures below are from the overlook and the fires that began while we were there.

An hour later, just outside another Israeli civilian community and near an Israeli Defense Forces (IDF) memorial, we watched as fires started in agricultural lands just a few hundred meters away from us—almost certainly from these balloons.

When I returned to the United States the day after witnessing these attacks, I emailed the woman I met in Kfar Aza and asked her how her community was doing. She informed me that another 10 devices had been recovered from just her community that day. The next day, several news outlets reported that the U.N. and Egypt mediated a cease-fire between Israel and Hamas to end the fire balloon attacks in exchange for economic relief.

It is beyond dispute that customary international law limits and prohibits certain “means and methods” of attack, particularly “indiscriminate attacks” during armed conflicts, and that individuals can be held criminally liable for their violations of these customary laws of war. Generally, “means of warfare” refers to the weapon system being used, while “method of warfare” refers to how the weapon is being used or the military tactic used. As Hamas has been using them, these incendiary balloon attacks violate numerous rules and customs of warfare—principally concerning the targeting of civilians and the use of indiscriminate weapons. The attacks also likely violate the prohibition on the use of incendiary weapons in this context.

The protection of civilians against the harmful effects of armed conflict is one of the foundational purposes of the law of war. Hamas’s employment of incendiary balloons violates both the principle of distinction and the prohibition against targeting civilians to spread terror, two related but distinct rules of warfare that specifically protect civilians from attack.

First, the principle of distinction requires that parties to a conflict must, at all times, distinguish between civilians and combatants, and that attacks may be directed only against combatants. In this case, the Israeli communities in the Gaza Envelope are purely civilian communities, surrounded by agricultural land. There are no static IDF bases or outposts in the area—certainly not within range of these devices.

Second, this use of incendiary balloons violates the independent prohibition on attacking civilians to spread terror. Both Additional Protocol I and II to the 1949 Geneva Contentions, along with the International Committee of the Red Cross (ICRC) Customary IHL Study, provide that “[a]cts or threats of violence the primary purpose of which is to spread terror among the civilian population are prohibited.” Regardless of the type of conflict, and regardless of the composition of the belligerents, attacking civilians to spread terror is strictly illegal. It is easy to imagine the civilian terror caused by the constant threat of one’s home, school or place of work catching fire. But there is also direct evidence that factually establishes the intent behind these attacks, provided by the notes that accompany some of the balloons.

I took this picture of one such note, written in both Hebrew and Arabic. The Hebrew-to-English translation was provided to me by a community member from Kfar Aza, and reads:

To the settlers of the Otef Aza (Gaza Envelope): If our letters don’t arrive to you by mail it will come with the balloons. If your army continues to kill our children on our eastern border and continues its silence it doesn’t bring you anything but defeat and regret and we will come with the incendiary balloons to kill you and burn the houses that you took from us—you should know—that Netanyahu lives in illusion if he thinks that continuing murdering children and continuing the siege will bring him the victory in the election and this is why we’ll continue to hit you with the balloons until you will end the siege. Gaza Fire Balloon Brigade

By linking these attacks to current domestic Israeli politics, and demanding a change in government policy vis-a-vis the Gaza Strip, the attackers are using terror as leverage in an attempt to force a change to government policy. In fact, this was somewhat successful: Israel eased restrictions in the Gaza fishing zone in return for Hamas promising to end the incendiary balloon attacks. By promising to end these attacks, Hamas, the de facto authority in Gaza, demonstrated that it had both knowledge of, and effective control over, the individuals making the incendiary weapons and illegally attacking civilians. This makes the attacks attributable to Hamas and not mere Palestinian civilians or protestors.

Attacking civilian communities with incendiary balloons as a means of warfare is clearly illegal. However, the use of incendiary balloons, at least in this context, is also illegal as a method of warfare insofar as the attacks are indiscriminate. There are three basic ways an attack constitutes an indiscriminate, and thus illegal, attack. First, indiscriminate attacks are those that are not directed at a specific military objective; second, they employ a method or means of combat that cannot be directed at a specific military objective; or third, they employ a method or means of combat the effects of which cannot be limited as required by IHL. Hamas’s use of incendiary balloons meets each independent definition of an indiscriminate attack.

In the case of the balloons, as stated previously, these attacks are aimed specifically at civilians and thus meet the first definition of an indiscriminate attack. The reliance on coastal winds to deliver the weapon and the imprecise timing of homemade fuses—both independently and together—violate the prohibition on using a means of attack that cannot be directed at a lawful target. Here, even assuming the existence of a lawful target within range of these incendiary devices, there is no reasonable way to employ them in a manner in which they will reliably reach the intended target. Lastly, the nature of fire itself is largely uncontrollable. This is even more so in the Gaza Envelope because of the dry summer climate and the open and agricultural land that makes up much of this area.

Finally, the use of incendiary balloons in this context likely violates the customary limitations on incendiary weapons, as reflected in the ICRC Customary IHL Study. Whether or not a prohibition against using such weapons has in fact crystallized into customary international law applicable to a noninternational armed conflict is not dispositive to the illegality of Hamas’s use of them—as Hamas is illegally targeting civilians—and highlights yet another potential way these attacks constitute a war crime.

Reports indicate that “close to 100 fires from incendiary devices” had been started in Israel just in the week of June 23, on top of the destruction that began in early May. This suggests the number of these devices being launched is far greater. Based on the resources necessary to sustain the construction and launching of so many incendiary balloons over a prolonged period of time, it is implausible that these attacks are the work of a few individuals. It is far more likely these attacks were a planned and coordinated operation by an organized group (or groups) supported by Hamas that were part of a campaign of terror against Israeli civilians used for political purposes.

It is important to document war crimes when and where they occur so that perpetrators can be held accountable, and so that an accurate and factual record is compiled. The international community should unequivocally condemn the targeting and threatening of civilians, the use of illegal weapons in armed conflicts, and the deliberate and organized strategy of committing war crimes to seek political change. Future engagement by the United Nations or third country intermediates, like Egypt, who are working toward peace in the region should seek the surrender of those individuals responsible for committing war crimes to stand trial before a fair and competent jurisdiction. Until impunity for war crimes ends, Hamas will likely continue to find it politically advantageous to commit them.