Mankind is extremely good at a lot of things, of which one of those things, quite regrettably, is the design of armaments that are quite effective in the indiscriminate killing of civilians, of which, the usage of cluster munitions, is one of those weapons of war, that has no legitimate part of nation-state actions against any other nation-state or enemy, real or imagined. Cluster munitions are bombs that are meant to open up mid-air to subsequently violently release a multitude of sub-munitions, thereby disbursing such sub-munitions so as to saturate a very large target area with a whole lot of damaging and very destructive bombing. Additionally, as in any munition, so created, not all of the sub-munitions are going to actually explode upon impact upon the ground or up in the air, thereby leaving a multitude of these unexploded munitions, embedded in the ground, of which such can subsequently explode, even years afterward, and thereby hurt or kill unaware civilians and children.
Fundamentally, the issue with cluster munitions is that they are specifically designed not to be smart and precise targeting weapons, but rather they are designed to deliberately do physical damage and kill human beings specifically over a vast area so as to wreak bloody havoc and create mayhem. To a very large extent, countries such as Russia, Israel, and the United States, who are not signatories to the Convention on Cluster Munitions (a treaty that bans the use of cluster munitions), are basically showing their contempt for the value and dignity of human life. Further to the point, the very countries that one would think that would be the most inclined to desire to use a weapon that is so gross in its targeting and that by design, will cover a lot of killing ground, indiscriminately, while also being quite cost effective, would be those nation-states that are both short on budget as well as being short on personnel to effect military operations, and thereby would see cluster munitions as a desirable weapon to utilize so as to do a lot of damage to perceived enemies, especially when that nation-state does not readily discriminate or overly concern themselves between those that are enemy soldiers and those that are civilians who are known to be in that target area.
The reason that countries such as Russia, Israel, and the United States, do not desire to give up their cluster munitions is that these countries prefer the flexibility of bombing other nation-states into sheer oblivion, and clearly don’t really care about how many civilians are killed, injured, or harmed in the doing of exactly that very thing, because those particular countries, believe strongly that their fellow countrymen are much more concerned about their own country's casualties, as compared to the nation-states that are being bombed by those cluster munitions. In other words, for example, the bombing of nation-states by the United States via the usage of their cluster munitions, risks a very minute percentage of American soldiers lives, while also being quite effective in the killing and harming of people within the targeted area, regardless of whether or not it strategically accomplishes its given purpose or not.
The bottom line, is that cluster munitions are a crime against humanity, because the design of these weapons are indiscriminate in their nature, and thereby should be seen as nothing more than brute force, that is purposely meant to unnecessarily make people that are simply inhabitants of specific nation-states, unduly suffer.