 Why are the aliens not sure if they can help the humans?
A gentle fancy for the Christmas Season—an oft-told tale with a wistful twistful of Something that left the Earth with a wing and a prayer. Earth was so far away that it wasn't visible. But this vast distance did not mean that isolation could endure forever. Instruments within the ship intercepted radio broadcasts and, within the hour, early TV signals. Machines compiled dictionaries and grammars and began translating the major languages. The history of the planet was tabulated as facts became available. The course of the ship changed slightly; it was not much out of the way to swing nearer Earth. "We've got to make or break," said the first alien. "It's not what they've done," said Bal, the second alien. They've had two world wars in one generation and that the third and final one is coming up you can't help feeling in everything they do." "The wrong diplomatic move, or a trigger-happy soldier could set it off. A meteor shower could pass over and their clumsy instruments could interpret it as an all-out enemy attack." "We'll just have to forget there ever was such a planet as Earth." Except for the one thing they lack, and that's quite odd, they seem exactly like us. "It is. "There is. "In a week we can't negate their entire history. There's nothing in this region of space our people want," said Ethaniel. "And how long can Earth last?
 They do not think they have enough time to intervene like they wish they could
 Their superiors would not approve of an intervention on this planet  They do not think they have enough time to intervene like they wish they could  They do not have experience with this specific type of military technology  They have no way of communicating with the humans in their own languages