Vastrap (Stand firm) is a small military airfield situated in the Kalahari Desert north east of Upington inside a 700 square kilometre weapons test range of the same name[1] belonging to the South African National Defence Force.

It was constructed to allow the SAAF to practice tactical bombing operations, and for aircraft to service the SADF's defunct underground nuclear weapon test site.

The area was selected for nuclear weapons testing due to its remoteness, low population density, stable geological formations and lack of underground rivers.

[5] The US then applied pressure on the South Africans for it to be closed;[6] France also insisted on closure, threatening cancellation of the Koeberg nuclear power station contract.

[7] David Albright reported that South African officials believed that an attempt to re-use the site in the late 1980s was detected by Western or Soviet intelligence agencies, and that this discovery influenced the Tripartite Accord.