In "Jedinstvo 1" reforms YPA eliminated most of its old divisional infantry organization and established the brigade and corps structure with some independent units under direct command of SSNO(equivalent of General Staff). Territorial defense also changed and laws and constitution was amended to address those changes. The Ground Forces converted ten of twelve infantry divisions into twenty-nine tank, mechanized and mountain infantry brigades with integral artillery, air defense and anti-tank regiments under corps structure. One airborne brigade was organized before 1990. The shift to brigade-level organization provided greater operational flexibility, maneuverability, tactical initiative and reduced the possibility that large army units would be destroyed in set piece engagements with an aggressor. The change created many senior field command positions that would develop relatively young and talented officers. In 1989. five independent divisions under general staff command and 25 partisans divisions under corps command were formed including many other battalions, regiments and batteries under different commands.