William Kristol is the chairman of one of the best known neo-conservative think tanks - The Project for the New American Century.

He is also in charge of a top neo-conservative magazine called The Weekly Standard.

Mr Kristol himself is a former White House insider, having been Chief of Staff to the Vice President under George Bush snr.

The Project for a New American Century (PNAC) has a mission to "shape a new century favourable to American principles and interests".

Democrats

It has been pressing for the US to use its military power to influence the world for more than a decade and wrote a letter to Bill Clinton in 1998 urging him to use 'military steps' to protect US interests in the Gulf.

Mr Kristol was raised in New York and educated at Harvard, but actually spent his early years working for the Democrats.

However, by 1976 he had become a Republican, and in 1985 was hired by Bill Bennett to work in the Department of Education.

He served as Dan Quayle's Chief of Staff under the first Bush administration and has worked for ABC Television, as well as running the Weekly Standard.