Are summoned/animated creatures able to make opportunity attacks?

@JeremyECrawford Are summoned/animated creatures (animate objects, conjure elemental) able to make opportunity attacks?

— Mike McTee (@OCJeriko) February 6, 2017

Any creature can make an opportunity attack, unless a rule says otherwise. #DnD https://t.co/M3vn67LY9w

— Jeremy Crawford (@JeremyECrawford) February 6, 2017