Sgt Johnson was among four Green Berets killed when their patrol was ambushed by Islamist militants: AP

Donald Trump has claimed it would be impossible for him to forget the name of a fallen soldier because he has “one of the great memories of all time”.

President Trump sparked controversy after being accused of not knowing the name of a dead soldier whose widow he phoned to console after he was killed in Niger.

Democratic Congresswoman Frederica Wilson, who was accompanying the family, said during the five-minute conversation President Trump failed to display the necessary tact or diplomacy needed for such a situation.

“Basically he said, ‘Well I guess he knew what he signed up for, but I guess it still hurts’,” Ms Wilson told CNN. “I heard what he said because the phone was on speaker.”

Myeshia Johnson claimed the US president struggled to remember the name of her fallen husband Sergeant La David T Johnson during a phone call with his family and the call made her "cry even worse”. She told Good Morning America: "I heard him stumbling [over] trying to remember my husband's name, and that's what hurt me the most."

"If he's putting his life on the line for the country, why can't you remember his name?" she added.

But President Trump has now sought to defend himself in a media conference and insisted he respected Ms Johnson and did not forget the name of her late husband.

He said: “I can only say this. I was really nice to her [Ms Johnson]. I respect her, I respect her family, I certainly respect La David - who, by the way, I called La David right from the beginning, they put a chart in front, La David, it says La David Johnson.”

“So I called right from the beginning, there's no hesitation, one of the great memories of all time, no hesitation."

Mr Trump said he had never met Ms Johnson but heaped praise on her, saying: "I think she's a fantastic woman, I was extremely nice to her, extremely respectful”.

Prior to this President Trump answered a question about whether he should be more civil by reminding reporters he is went to an Ivy League college and is “very intelligent”.

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Sgt Johnson was among four Green Berets killed when their patrol was ambushed by Islamist militants. Mr Trump called his widow, Ms Johnson, while she was travelling with her family to meet her husband’s casket at Miami International Airport.

Last week, President Trump denied telling Ms Johnson her husband “knew what he signed up for" moments before she wept over his coffin.

He claimed not only was Ms Wilson, the Florida congresswoman who reported the phone call, wrong but that she had gone so far as to intentionally lie.

"Democrat Congresswoman totally fabricated what I said to the wife of a soldier who died in action (and I have proof). Sad!" he wrote on Twitter.

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