PJ Crowley was, until two weeks ago, US Assistant Secretary of State for Public affairs.
He resigned under heavy political pressure after describing the Pentagon's treatment of Bradley Manning, the US soldier suspected of spilling secrets to Wikileaks as "counterproductive and stupid".
Private Manning is being held at a maximum security jail, in shackles and in solitary confinement.
In an exclusive interview for HARDtalk Mr Crowley told Stephen Sackur he didn't regret expressing his views, but declined to say whether he had been asked to resign.
You can watch the full interview on BBC World News on Monday 28 March 2011 at 2030 GMT and again on Tuesday 29 March at 0330, 0830, and 1530 GMT and on BBC News Channel at 0030 and 0430 BST.
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