Question: What was Niel Barnard title during F. W. de Klerk state presidency from Aug 1989 to May 1994?

Context paragraphs:
Johannes de Klerk: Johannes "Jan" de Klerk, DMS (22 July 1903 – 24 January 1979) was a South African politician.  He was the father of F. W. de Klerk, the last State President of South Africa.

Mandela and de Klerk: Mandela and de Klerk is a 1997 television film directed by Joseph Sargent.  Starring Sidney Poitier and Michael Caine.  it documents the negotiations between De Klerk and Mandela for the transition to end apartheid in South Africa and was nominated for numerous awards in 1997 and 1998.

1990 in South Africa: 1990 in South Africa saw the official start of the process of ending Apartheid.  President of South Africa, F.W. de Klerk announced plans to end apartheid.  President De Klerk unbanned organisations that were banned by the government including the African National Congress, the South African Communist Party and the Pan Africanist Congress.  The African National Congress' armed wing, Umkhonto we Sizwe, suspends its armed activity within South Africa.  Political prisoners including Nelson Mandela were released.  Nelson Mandela met ANC leader Oliver Tambo for the first time in 28 years at a meeting in Sweden.  Mandela also traveled to England to thank the people for their support in the campaign to free him.  South Africa withdrew its troops from Namibia, which was granted independence.  1990 also saw marches in support and against the formation of a new post-Apartheid South Africa.

Thom de Klerk: Thom de Klerk (Thomas Johannes Josephus) (the Netherlands, the Hague, May 10, 1912 - Abcoude, October 13, 1966).  Dutch bassoonist, double reed maker, music teacher, conductor and music director.  Thom de Klerk was the first solo bassoonist of the Royal Concertgebouw Orchestra from 1935 until 1966.  He was successful with the directors Willem Mengelberg, Eduard van Beinum and Bernard Haitink.  Guest directors like Eugen Jochum, Arturo Toscanini and Pierre Monteux made special requests for his presence in the orchestra.

FW de Klerk Foundation: The FW de Klerk Foundation is a nonpartisan organization that was established in 2000 by former South African President Frederik Willem de Klerk.

Niel Barnard: Dr Lukas Daniel 'Niël' Barnard (born 1949) is a former head of South Africa's National Intelligence Service and was notable for his behind-the-scenes role in preparing Nelson Mandela and South African presidents P.W. Botha and F. W. de Klerk for Mandela's eventual and, as he saw it, inevitable, release from prison and rise to political power.

Veronica de Klerk: Veronica Cecilia de Klerk (born 26 November 1947) is a Namibian women's rights activist.  Veronica Cecilia De Klerk is a former television news presenter and actuality radio programme presenter with the Namibian Broadcasting Corporation in Namibia, and was educated in Germany in the "Promotion of Women's Self-help programmes in developing countries".

F. W. de Klerk: Frederik Willem de Klerk, DMS (] ; born 18 March 1936) is a South African politician who served as the country's State President from August 1989 to May 1994.  He was the seventh and last head of state of South Africa under the apartheid era.  De Klerk was also leader of the National Party (which later became the New National Party) from February 1989 to September 1997.

Marike de Klerk: Marike de Klerk (17 November 1941 – 4 December 2001) was the First Lady of South Africa, as the wife of State President Frederik Willem de Klerk, from 1989 to 1994.  She was also a politician of the former governing National Party in her own right.  She was murdered in her Cape Town home in 2001.

Cabinet of F.W. de Klerk: The cabinet of FW de Klerk was in office from 16 August 1989 to 11 May 1994.

Supporting paragraphs: Niel Barnard F. W. de Klerk
Answer: head of South Africa's National Intelligence Service