It's a US mess kit knife, 1941 to 1950. For eating with, rather than a cooking knife.

One of the difficulties with keeping an army in the field is feeding that army. Over the years, there have been many solutions to that problem, with varying degrees of centralisation and decentralisation. Solutions have including transporting food (mostly grain) by cart/wagon or ship, acquiring food locally (foraging, buying or extorting food from the locals, in some rare and extreme cases eating the locals), and soldiers bringing their own food with them (which often results in armies that can only stay in the field for a short time). For a long time, the mainstay of army rations was grain. Often, this was in the form of whole grain, which kept better than flour and much better than most types of bread. The problem with whole grain is that it needs to be cooked before being eaten, and can take a long time to cook unless ground into flour. Thus, grinding grain and cooking grain (whether as porridge or flatbread or other bread) was a key part of supporting an army. For an interesting discussion by u/Iphikrates of the provisioning of ancient armies, see https://www.reddit.com/r/AskHistorians/comments/go4fa4/how_did_ancient_greek_armies_cook_eat_on_campaign/frdzpwl/

Modern warfare brought difficulties. The firepower-dominated battlefield mean that even where/when field kitchens were used by armies, they were often unable to operate in the front lines. It could be difficult to bring cooked food forward to the soldiers. Thus soldiers needed to be able to feed themselves in the front lines. Cooking was not always easy or even possible; thus, food that was already cooked, with a long shelf-life, and suitable to be carried by soldiers as emergency rations, was highly desirable. Various solutions included hardtack (biscuit), dried foods, and canned foods (there were even ancient solutions, with Indian armies carrying sugar as emergency rations). From the Boer Wars through to early WWII, the front lines of the British Army lived on canned beef and hardtack, accepted by the soldiers as better than starvation, but rarely liked, and teas (much more liked than the food). If necessary, the canned beef could be eaten as-is straight from the can (less than desirable especially when the contents had separated into a solid block of fat at the top of the can and sludge at the bottom, in two decades of storage since being canned for WWI) and the hardtack/biscuit soaked in water or tea. German emergency rations could include canned bread and canned liverwurst.

US WWI emergency/field rations were similar to the British: hardtack and bacon or canned beef. While the British soldiered on into WWII with such rations, the US Army recognised that something better was desirable, which led to the development of rations such as the C-ration (in 1938) and K-ration (in 1942).

Already-cooked emergency/field rations freed soldiers from the necessity of cooking their own food in the front lines. Thus, simpler cookware that could be used for both heating such rations and eating them was useful. This is the environment that spawned the modern mess kit - a combination of eating utensils and simple cooking tools sufficient to heat rations. Before this, when soldiers needed to cook from scratch on the front lines, proper cookware was normal (not necessarily carried by every soldier, since they could cook in groups), and simple plates/bowls were sufficient. Before the US first issued mess kits in the 1870s, soldiers would provide their own eating and cooking gear. Originally, wood of pewter plates/bowls were common, but tin-plated iron largely replaced them as it became widely available.

In 1874, the US issued its first mess kits, consisting of a "meat can and plate combined", with folding handle, and a lid (which could also be used as a plate). This was suitable for eating food cooked and distributed by field kitchens, or reheating emergency rations. It was lighter than carrying separate cooking and eating gear. These first US mess kits are quite recognisable as ancestors of even the last mess kits issued by the US Army (the issued mess kit came to an end early this century due to the MRE). Cutlery was also part of the mess kit. Again, the first versions issued by the US Army are recognisably ancestral to the later versions. The first US mess kit knives were much like yours, but without the hole in the handle. The US Army adopted a new pattern of cutlery in 1926, with holes in the handle. But with vast numbers of the 1910 pattern having been made for WWI, the new pattern was not manufactured until 1941. In 1934, the Army directed that the 1910 pattern cutlery be modified into the new pattern; some were but large numbers were not.

In 1941, when mess kit cutlery manufacture began again, a new specification included plastic handles. However, most manufacturers were not equipped to make the plastic handles, and most new mess kit cutlery was made to the 1926/1934 standards, with cast aluminium handles. This includes your knife. In 1950, these were replaced with simple knives that were one-piece stampings from sheet metal.

For more on US Army mess kits and their evolution (and haversacks, and canteens, and canteen cups), see https://history.army.mil/html/museums/messkits/messkit.html