He said he was "angry and appalled" by Mr Trump's handling of ongoing protests over the death of African American George Floyd at the hands of police.

Mr Mattis berated Mr Trump's "abuse of authority" - and backed protesters seeking to uphold American values, as did ex-President Barack Obama.

Mr Trump has described Mr Mattis repeatedly as an "overrated general".

Mr Mattis quit in 2018 after Mr Trump decided to pull US troops out of Syria.

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