I read this story some time around 2000. It wasn't brand new when I read it, but I think it was close. It was in a collection of sci fi short stories, and it was by a relative unknown; the central conceit of the book was that it was vaguely educational in that you could learn a bit about the craft of writing. The authors themselves were newcomers but each story was followed by a paragraph or short essay analyzing the work and describing why the story functioned well written by a more famous or experienced author. Unfortunately I can't remember a single name. I think the cover of this collection was black with the title in fat green letters, but I could be imagining that memory. I don't remember a common theme among the stories other than science fiction, but this particular piece was really rayguns-and-rocketships lighthearted adventure stuff.
The story I'm looking for concerns a man on an alien planet with a sizeable culture of sophisticated intelligent creatures. He's there on some kind of cultural or diplomatic mission: to establish diplomatic relations, or to evaluate the locals as allies, or open a trading partnership or something similar.
The thing is, these locals have a problem. They're under threat from some hostile power, either aliens from another planet or some kind of local malefactors; I think it's the former. They want help from Earth, but they might not necessarily believe it will help much, or that Earth will bother. (Our main character knows the Earth Fleet or whatever can squash the enemies like a bug; maybe they just don't believe him.) The protagonist becomes personal friends with several of the aliens he's dealing with and is bitterly torn about whether to help them or not: he wants to for personal reasons, but in an official capacity he can't signal for help because they just don't check all the boxes. There's some niggling problem that won't let him summon the Fleet, even though deep down he knows (and of course we do too) that the locals are the good guys and their enemies are big meanies who deserve a solid sock to the nose. Furthermore his signal will take weeks or something to have an effect: the communication has to reach HQ and then the fleet has to crank up and set out and of course, Space Is Big. So they might not even be there in time.
In the end, the bad guys attack, the locals are all running for air raid shelters, and our hero decides to quit his job, pick up a laser gun or whatever and throw in with his new buddies, but not before pressing the big red "HELP" button. (This is metaphorical. I don't actually remember anything about the specific weapons or whether there was a button; he just calls for aid.) To his astonishment, seconds later the sky is black with Earthican ships all there to save the day, and they do, and everybody lives happily ever after.
In the denoument the main character talks to his boss while medical teams and aid workers shake hands with the locals and pass out emergency rations and his boss explains with something like "You knew what was going on here from the beginning, and so did we; we mobilized weeks ago and have been hanging out just around the block waiting for you to give the word."
The thing that always stood out in my memory was the page or so where the Earth ships show up. It was blistering prose, conveying overwhelming justified force; I was reminded of it recently watching the show One Punch Man. The author goes on a rampage for sentence after sentence, making it clear The Bad Guys Have Made a Big Mistake. It was almost startling, to me, at the time ... that feeling when Gandalf brings the Riders of Rohan over the hill with the sun at their backs.
So I read this in American English around the year 2000 and I don't remember much about the main character, which means he was probably either a generic white guy or just barely described at all. I was in my late twenties then and it was a relatively new book, nothing from the fifties or even the eighties, I don't think. I can't rule out 1995. I've been asking this for years online, but I can't remember where; it's been several years.