This is the first part of the three stage Murrain Operation;  the final target of this operation is the Alien headquarters on Lanios III.
This purpose of this mission is to destroy any potential reinforcements the Aliens could send in to stop your destruction of their headquarters. 
Your target is a moderate-sized defensive outpost that is being used as a staging area by the enemy.  It sits in a canyon deep in Alien territory.
Your insertion site is to the northeast of the opening of the canyon system.  Stealthily approach the base while watching for enemy patrols.
You must destroy all enemy buildings in the outpost.  Once this task is accomplished picking off the straggling Alien survivors will be undertaken by the Lanios Defense Force's 2nd Battalion. 
Your skills will be needed elsewhere shortly.  Good hunting Merc!
