US presidential debate: Clinton's spokesman tells Trump 'go f*** yourself' over Capt Humayun Khan claim

Advisor Jesse Lehrich later apologised for his language

An image of fallen U.S. Army Capt. Humayun S. M. Khan is displayed on a screen as his father Khizr Khan delivers remarks on the fourth day of the Democratic National Convention (Getty Images)

One of the many issues on which Donald Trump and Hillary Clinton clashed in the second presidential debate was the decision to invade Iraq.

Mr Trump insisted he was opposed to the war, despite contemporary quotes suggesting otherwise. He also criticised his rival for voting as a senator to authorise the war and said that a US Army captain, Humayun Khan, killed in Iraq in 2004 would still be alive if he had been president at the time.

Captain Khan is an American hero and “he would be alive today if I had been president”,” he said.

The comments of Mr Trump - who famously clashed with the parents of Mr Khan after they publicly spoke out against him at the Democratic National Convention - were too much for one of Ms Clinton’s advisors.

“hey, @realDonaldTrump – regarding your claim that Captain Khan would be alive if you were president,” wrote Jesse Lehrich, Ms Clinton’s foreign policy spokesman. “Go f*** yourself.” #debate

He later apologised for using such language. “I want to apologise for the clearly inappropriate nature and language of this personal tweet. Sorry all” he said.