Water On Mars

In "The Martian Way" by Isaac Asimov, as far as I can remember, Earth stopped shipping water to Mars so the Martian colonists started to import it from the Saturnian rings.

In Protector by Larry Niven, a human protector exterminated the Martians by deflecting an ice asteroid onto a collision course with Mars.

In The Fleet Of Stars, 5, the Nantai etaine mines a lode of water which is sold by a Lunarian organization called a courai. 

Mars loses water because molecules escaping into the atmosphere are cracked apart by ultraviolet radiation with the oxygen binding to rocks and the hydrogen escaping into space. 

Because the Synesis - the cybercosm-dominated civilization in the inner Solar System - has stopped sending water, the Martians now have four options:

live underground;

leave Mars;

build ships and robots to get ice from the Kuiper Belt;

deal with the Proserpinans.

The fourth option seems best: free human beings together against the cybercosm.