Well, if you want to keep US locale, but include utf-8 support do next:
-edit as root /etc/profile.d/lang.sh with your favourite editor
-comment this line with # sign
export LANG=en_US
-uncomment this line (a little below):
export LANG=en_US.UTF-8
That should solve problem for you.

Else, you can set up locale for your language. Just type
locale -a command, find line that suites your language and put it in edited file by replacing current setting. In example, for my language (Serbian) I would replace
export LANG=en_US.UTF-8 with
export LANG=sr_CS.utf8.