We already have an agreement to trade freely with them, but having an alliance will make them more likely to be more friendly or giving when we do it in the future. If they call on us for military support, we need to have a damn good reason to say no, but it's likely we'll only be called on for that if the clan in question can't handle things themselves. We should be allies, not mercenaries. The Commander wouldn't let us be used like mercenaries.