The speaker is being praised by other people. They call the speaker strong, good, safe and dependable, a soldier protecting their own. The praise sounds kind, but the speaker doesn't take it as comfort. Something in it feels off.
The second stanza turns the compliment into an argument. If you call me a soldier, the speaker says, then there must be a war. But the war they describe is "one that's never happened," a fight that should have taken place and is "still waiting to." That suggests the speaker has been strong in a situation where no real confrontation ever came, perhaps because the thing that needed fighting was never faced. The poem doesn't say what that is, and the poem's own details leave it open.
The mood is quiet, tense, and a little bitter. The lowercase, plain voice sounds calm, but underneath there is held-back anger, which fits the title "Belligerent." The speaker seems stuck between being admired and feeling unfinished.