 This site was chosen because of it was co-located with the HAWK Missile Batteries of the 1st Light Antiaircraft Missile Battalion and the United States Air Force's Panama Air Control Faility.The site also provided excellent line of sight to United States Seventh Fleet ships operating in Yankee Station in the Gulf of Tonkin.MACS-4 arrived in Vietnam in June 1967 and was established and operating on top of Monkey Mountain beginning 6 July 1967.