US State Department spokesman PJ Crowley has resigned after causing a stir by describing the Army's treatment of the suspected WikiLeaks leaker as "ridiculous" and "stupid".
Mr Crowley said in a statement that he took responsibility for the remarks and that, given their impact, he had submitted his resignation to Secretary of State Hillary Clinton.
President Barack Obama said on Friday that the Pentagon had assured him the Army private believed responsible for the largest leak of classified American documents ever was being held under appropriate conditions.
Bradley Manning is being held in solitary confinement for all but an hour every day at a Marine Corps brig in Quantico, Virginia.
He is stripped naked each night, and given a suicide-proof smock to wear to bed.