 Complete the following phrase:  Due to the absence at that historical stage of special units as part of the Internal Troops, special purpose units of the GRU were involved in cases of suppression of riots or acts of mass civil disobedience. Examples of the involvement of the 15th Brigade military personnel for such purposes in the 1960s and 1970s are: ensuring the quarantine area during the epidemic of cholera in the Karakalpak Autonomous Soviet Socialist Republic in the late summer of 1965, blocking the streets of Tashkent affected by the 