I understand but this seems different. Paying money to the SA Amb to the US for 20 years. I wonder if this is coming out now because relations with SA have become so bad? Probably a lot of intriguing details we will never hear about.
Take a look at the timeline.
http://news.bbc.co.uk/2/hi/business/6182137.stm
Looks like the investigation was started and then stopped before it was finally opened again.
Unless BAE Systems is a wholly-owned subsidiary of a domestic stock corporation, all of which are covered by U.S. law forbidding such practices, no U.S. law has been broken. Since it appears that the UK has a similar law, then it looks like both BAE Systems and the Ministry of Defence have a problem in the UK. Imagine if the Pentagon approved such an arrangement to a U.S. defense contractor.