Robert Gates and President Barack Obama
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Pentagon ex-head Gates criticises Obama

8 January 2014 Last updated at 15:56 GMT

Former US Secretary of Defense Robert Gates has written a book strongly criticising President Barack Obama's handling of the war in Afghanistan.

In Duty: Memoirs of a Secretary of War, Mr Gates says that the president was sceptical that his administration's Afghan strategy would succeed.

"I never doubted [his] support for the troops, only his support for their mission," Mr Gates writes.

Mr Gates was Pentagon chief under Presidents Obama and George W Bush.

Nick Childs reports.