Silence their Cries is a mission on Kaldir.
Brood mother Na'fash had traveled here to create stronger claims. Sarah Kerrigan and a small number of zerglings landed on the moon in order to reclaim the Na'fash Brood. She discovered feral roaches which she brought onto her side, along with yeti.
The moon was constantly struck by cold windstorms, which would freeze the zerg in place and force a local protoss base to raise its shields, but had no effect on the yeti. As a result, Kerrigan wished to take DNA from a pair of yeti matriarchs.
The zerg encountered Na'fash's corpse... the protoss had gotten to her first. The high templar in charge, upon noting the presence of Kerrigan, attempted to warn Shakuras. Unable to reach the far-off Dark Templar homeworld with the Khala, he instead used psi-link spires. Kerrigan tasked her forces to destroy these spires before they could be activated.
Kerrigan destroyed the spires, prompting the protoss to retreat. Kerrigan then ordered her forces to finish off the protoss before they could travel directly to Shakuras and get their warning off.