Since I first read it (and Russell's other brilliant books such as Men, Martians and Machines and Three to Conquer) in my early teens, I have regarded Wasp as one of the true SF classics. It ranks with Bester's The Demolished Man and Tiger! Tiger!, as well as the best of Clarke and Heinlein, although its sardonic tone has more in common with Robert Sheckley.
Although set in a future a few centuries ahead, when Earth is at war with the Sirian Combine, Wasp is directly transplanted from conventional warfare of the Second World War era. Indeed, I don't know why it took so long to dawn on me that the Sirians are analogues of the Japanese, while the noble Earthmen are essentially 1950s Americans. Oh sure, the Sirians are purple instead of yellow - but they are short, bandy-legged, and fanatical. To clinch it, their dreaded secret police is called the Kaitempi: compare the actual Japanese Kampeitei.
The Sirians have a great advantage in numbers, but the Earthmen are smarter. How to make the most of their quicker wits and superior technology? One way is to drop secret agents behind enemy lines to sow confusion, dissension and destruction. The result is dramatic, convincing and (in parts) riotously funny.