In mid-May, United States Secretary of Energy Steven Chu assembled a team of nuclear physicists, including hydrogen bomb designer Richard Garwin and Sandia National Laboratories director Tom Hunter.  Oil expert Matthew Simmons maintained that a nuclear explosion was the only way BP could permanently seal the well and cited successful Soviet attempts to seal off runaway gas wells with nuclear blasts. A spokesperson for the . Energy Department said that "neither Energy Secretary Steven Chu nor anyone else" ever considered this option.   On 24 May BP ruled out conventional explosives, claiming that if blasts failed to clog the well, "we would have denied ourselves all other options."