Eric Frank Russell was British, and served in military intelligence during World War II. He was also one of the most prominent humorous SF writers of his time.
Wasp is, as Jack Chalker says in his introduction, "the only World War II novel that I know of set in the Sirian Interstellar Empire". It's about a man who is recruited to serve undercover in enemy territory committing acts of sedition and terrorism, a 'wasp' designed to demoralize and distract the enemy and commit resources that would otherwise be put to use on the front lines.
Our wasp is named Mowry, and he's very effective. Minor alterations to his appearance make him appear to be a native-born Sirian. With some fiscal and technological help, he infiltrates himself into the police state and begins wreaking havoc.
There's not a lot of real science fiction here - 'scratch the Sirian's purple skin and find Imperial Japan underneath', says Chalker. It's almost entirely a spy novel set on another planet. But it is very fun and should be enjoyed by fans of Bond and his ilk.
So: the terrorism. Here we have a guy who goes about undercover and commits acts of violence against a civilian populace. That's not too popular these days. Why don't I feel repulsed by it? Well, this is clearly modeled after World War II, which was a conflict that required all-out commitment from the Allies. The niceties were not observed, because they could not afford to observe them. Germany and Japan wanted to invade and control Allies and were aggressors in the conflict. Casting the Sirians as the Axis in WWII makes civilian attacks less surprising. I can't pretend to be shocked by a character blowing up a hotel room in the context of Hiroshima.