bash conditional variable assignment cli not what I expected

Can anyone explain what's going on with DR here?

user@host:~# DRYRUN=true
user@host:~# echo "$DRYRUN"
true
user@host:~# $DRYRUN && export DR="-n"
user@host:~# echo $DR
user@host:~# $DRYRUN && export DR="-n" && echo $DR
user@host:~# $DRYRUN && export DR="-n" && echo "$DRYRUN --- $DR"
true --- -n
user@host:~# echo $DR
user@host:~# echo "$DRYRUN --- $DR"
true --- -n
user@host:~#

I Just want to assign DR to the string "-n" when DRYRUN is set to true but what I'm getting is confusing