It's all in the little details isn't it? I like this too; when writers put in all the nitty and the gritty:
The Marine kept his sight moving, tracking not just the conversation but the space around it. A stray glance, a shift in formation, a hand twitching toward a weapon—any of those could be the sign that things were about to turn.
The wind picked up again, rustling the dry brush around him. Wes exhaled slowly, barely moving, waiting.
Like this excerpt. That bit about the wind just adds extra dimension to it. And, I rather think, helps build up the tension and ratchet up the drama-rama. Neatly done!