Looking downbeat and weary, Joe Biden walked to the podium in the East Room of the White House to deliver an address following the deaths of US service members in Afghanistan.

"It’s been a tough day," the US President began.

He called the troops who lost their lives "heroes" and described the military as the "backbone of America".

He said he was outraged and heartbroken by the deaths.

Joe Biden is known for compassion and empathy and there were signs of that as he recalled his son Beau who had served in the US military in Iraq and died of brain cancer in 2015.

He spoke about suffering and loss and bowed his head for a moment’s silence.

But there were also tough words from the US President as he delivered a warning to the terrorists who carried out the attacks at Kabul airport.

"We will not forgive, we will not forget, we will hunt you down and make you pay," he said.

Mr Biden said he has directed his generals to draw up plans to strike ISIS-K leadership and assets.

He also vowed that the evacuation mission would continue and that the United States would not be intimidated by terrorists.

The political pressure on the US President over the botched withdrawal from Afghanistan may well have eased if there had been a successful evacuation from Kabul.

Now that American and Afghan lives have been lost, the criticism of Joe Biden will intensify and there are likely to be more "tough days" ahead.