Don't know about what S. Africa thought of Serbia, but we do know that Milosevic's Yugoslavia & its successor Serbian entities were selling weaponry to include explosives for use in artillery shells, rocket fuel, cruise missile technology, maintenance assistance and even military and defense technology advisers throughout the 90s and right on up to 2002; all in violation of international sanctions and in direct opposition to U.S. interests. Possible that American soldiers have been killed or maimed in Iraq with explosives provided by the Serbs. The Yugos/Serbs have done much the same with Qaddafi's Libya, so who knows how much stuff has gone further to Al Qaeda and other terrorist groups.
The U.S. government has protested and Kostunica has been doing his best to get this under control, but corruption & anti-American attitudes among Milosevic hold-overs have made it tough to root it all out. Under Milosevic, Serbia was an enemy of the USA and a friend to our enemies.
above message references Serbian arms sales to Hussein's Iraq.
Actually, didn't Yugoslavia have ties with both Iraq and Libya dating back to the 1970s, at least?