Shoigu arrived in Minsk for talks with Khrenin earlier in the day.
"Defense ministers of Belarus and Russia signed a protocol to the agreement between Belarus and Russia on the joint provision of regional security in the military sphere of December 19, 1997," Valery Revenko said on Twitter.
Shoigu and Khrenin also discussed issues pertaining to bilateral military and military-technical cooperation, according to Belarusian state-run news agency.
The 1997 agreement provides for protection of national and common interests of the Union of Belarus and Russia against potential and real military threats.