Concealed losses?

We know all governments and air forces conceal losses especially those in non-war or covert circumstances- I would like members to put any information they have in this thread amd generate discussion. I will start with some thought provokers:

1) I have heard PAF shot down Israeli F-15 while it was overflying Pakistan from India
2) Israeli mercenaries flew in Africa in support of South Africa and Ethipia in regional conflicts.
3) Russia sent AWACs to India in 1971 war with Pakistan- and used this against pakistan
4) US F-117 shot down over serbia was shot by MiG-29
5) In Gulf War, US used `accidents’ to cover up many air losses- they accept 40 odd losses, actual losses may be over 100.
6) Israel lost over 20 planes in 1982 to Syria in air combat- western accounts have always maintained 0-2 for years.