President Biden's speech and response to the situation has been criticised by Republicans.

US Senate Minority Leader Mitch McConnell described the situation in Afghanistan as "an unmitigated disaster".

"The Biden Administration's retreat will leave a stain on the reputation of the United States. And it didn't have to happen this way," he added.

Senator Marco Rubio accused Biden's allies of "trying to twist the Afghanistan debacle into a debate about the decision to leave".

Mike Rogers, who serves as the ranking member of the House Armed Services Committee, said: "His words are no comfort to the women and children now forced to live under the repressive Taliban regime.

"Afghans are so desperate to flee the Taliban that they are clinging onto departing American aircraft", US media reports him as saying, external.

Michael McCaul, ranking Republican of the House Committee on Foreign Affairs, also criticised Biden's speech.

The US state department says its negotiators are continuing to engage with the Taliban.

In a briefing on Monday, spokesman Ned Price declined to say if the US still recognises Ashraf Ghani as the country's president.

He said it was "something that we are working on with the international community".

Price added that the US would maintain a diplomatic presence at Kabul's airport as long as "it is safe to do so".

Image source, EPA

Here's a roundup of today's key developments

• There was chaos at Kabul's airport as thousands tried to flee. At least five people have been reported killed
• All flights were halted but the airport has since reopened under US control
• Both the US and UK announced extra troop deployments. The UK is sending an additional 200 troops while the US will deploy another 1,000
• US President Joe Biden defended the decision pull out of Afghanistan but admitted that events developed quicker than he thought
• He added that troops will secure the airport's airfield, take over air traffic control and ensure the continued operation of civilian and military flights
• Biden warned that if American troops are attacked by the Taliban, the US would "defend our people with devastating force"
• People in Afghanistan have spoken to the BBC of their fear of living under Taliban rule, with many saying they are searching for a way out
• Hundreds of Afghan forces have arrived in Uzbekistan over the past 48 hours

Paul Adams
BBC diplomatic correspondent, Jerusalem

Image source, Reuters

As the Taliban returns to power, Afghanistan's neighbours are all looking on, wondering what's in it for them.

China says it wants friendly relations with the Taliban. It hosted the group's political chief, less than a month ago.

And while the West's ignominious departure might seem like a source of satisfaction to Beijing, China worries that the reappearance of a fundamentalist Islamic regime in its backyard could lead to instability among its own Muslim Uighur population.

Russia, still scarred by its own experience of fighting in Afghanistan in the 1980s, has also reached out to the Taliban, already holding talks in Kabul.

Iran and Pakistan are both home to vast numbers of Afghan refugees. Both have had complicated relations with the Taliban, especially Pakistan, which played a major hand in promoting the movement in the early 1990s.

America may have left, but Robert Hannigan, the former head of the British intelligence agency, GCHQ, says this is not a country Washington can walk away from.

"The history of Afghanistan really illustrates the problems of being a country caught between these great powers," Hannigan says.

"This is a moment when we really need the United States to re-engage with the world, to do business with regimes that we don't find easy to work with, like Russia and China.

"The Biden administration has been very clear that we need to find a way of working with them on things that matter to us all, like climate change and like Afghanistan."

In the 19th Century, they called it the Great Game - Britain and Russia tussling for influence in Afghanistan.

It's a game that persists to this day, with a multitude of actors. The West may be battle weary, but Afghanistan still matters.

Tara McKelvey
BBC News, Washington

Image source, Getty Images

In an image released by the White House from the president's Camp David retreat, Joe Biden is seen sitting by himself at a table, speaking with advisers in a video conference.

He appears isolated and secluded.

For many, his isolation was a symbol of how the US was perceived on the world stage. US allies were appalled by his decision to withdraw troops from Afghanistan in the manner that he did.

Then, on Monday, he walked alone into the White House's East Room to talk about the crisis.

The room, with its high ceilings, seemed unusually empty. I sat there, along with other reporters.

White House Press Secretary Jen Psaki was there, too, thumbing through his speech.

Vice-President Kamala Harris was not. She was in the green room, a press assistant told me, waiting. I ran into Harris afterwards in the West Wing, and she waved, as she walked purposefully in the direction of the Oval Office.

Biden chose the setting, and the small number of players on stage, because he wanted to emphasise that he alone had made the decision to pull the troops, and that, despite the mayhem, he stood by his decision.

"The buck stops with me," he told us, and the rest of the world.

A moment later, he turned, and walked away. Alone, as before.

A striking image shared on social media shows hundreds of people on a US Air Force C-17 aircraft on Sunday as it left Kabul.

According to Defense One, external, who obtained the image from the military, some 640 people were onboard the aircraft, far more than its listed capacity.

Scores of Afghans, who had been cleared to evacuate, managed to get onto the aircraft's half-open ramp. Instead of forcing them off, the crew decided to take-off.

That is in stark contrast to images on Monday - when thousands of people crowded Kabul airport as they sought to flee the country. Planes were temporarily grounded, and US forces shot dead two armed men as the chaotic scenes unfolded.

Image source, EPA

After a flurry of news out of Washington, let's take a look at the latest from the Afghan capital after a chaotic, dramatic, day.

Kabul airport, where at least five people are reported to have been killed as thousands tried to leave the country, has now reopened under US control.

Flights at the airport were grounded earlier after people started running to planes on the tarmac. Some clinged to them in a desperate attempt to escape the country.

US Marines have since arrived on board C-17 military aircrafts, officials at the Pentagon told reporters.

Separately, Reuters news agency is reporting that a German military aircraft has landed in Kabul to evacuate foreign nationals and local staff.

Countries such as the US, Germany, the UK, and Canada are using military planes to pluck their nationals out of Afghanistan, while scrambling to evacuate Afghans who worked with their troops.

Image source, AFP via Getty Images

Mark Kimmit, the former assistant secretary of state under President George W Bush, has described President Biden's address as a "classic red-herring speech".

"What we are talking about, why he [Biden] was on the podium has absolutely nothing to do with the decision to withdraw," Kimmit told the BBC.

"Heck, every president wanted to withdraw - President Bush, President Obama, President Trump, and now him.

"That’s not extraordinary, and nobody would disagree with the fact that we should be leaving. Nobody wants to stay one year, five years, 10 years - that’s not the issue.

"The issue is the shambolic execution of the withdrawal, which I think calling it a hasty withdrawal is kind. This was cut and run, plain and simple," Kimmit said.

Image source, EPA

During his televised address from the White House earlier, President Biden laid out the US mission going forward. He said:

• 6,000 US troops are being deployed to assist with the departure of US and allied civilian personnel from Afghanistan
• The US will evacuate Afghan allies and vulnerable Afghans to safety outside the country
• Troops will secure the airfield, take over air traffic control and ensure the continued operation of civilian and military flights
• Thousands of American citizens living in Afghanistan will be transported out
• Through military assistance, Operation Allies Refuge - which selects at-risk Afghan civilians - will continue to provide a route out of the country for some eligible citizens

For those of you just joining us, here are the key points from President Biden's speech:

• The US president said he stood by his decision to withdraw troops from Afghanistan, adding that he would not pass the war on to a fifth president
• He said the 20-year mission was not meant to be about "nation building" or "creating a unified, central democracy", but was designed to prevent a terrorist attack on American soil
• Biden conceded that the country had folded "quicker than anticipated"
• He said American troops were trying to gain control of the airport and take over air traffic control
• Biden also warned that if American troops are attacked by the Taliban, the US would "defend our people with devastating force"

You can read our story on his comments here.

"We've made it clear to the Taliban [that] if they attack our personnel, or disrupt our operation - the US... response will be swift and forceful," says Biden.

"We will defend our people with devastating force if necessary."

"I will not pass this responsibility on to a fifth president," he adds, repeating a line he has often said since his April decision to leave Afghanistan by September.​

"I am deeply saddened by the facts we now face but I do not regret my decision to end America's warfighting in Afghanistan."

"I am the president of the US, the buck stops with me."

Biden says Washington will "continue to push for diplomacy" in Afghanistan.

"Now we're focused on what is possible," he says, adding that the US will:

• Continue to support the Afghan people
• Lead with our diplomacy, our international influence and our humanitarian aid
• Push for regional diplomacy and engagement to prevent violence and instability
• Speak out for the basic rights of the Afghan people

"I've been clear, human rights must be the centre of our foreign policy, but the way to do it is not through endless military deployments," he adds.

Responding to criticism that the US did not act swiftly enough to evacuate threatened Afghan civilians, he says the reason for the delay was two-fold.

"Afghans did not want to leave earlier," he starts.

The other reason was that the Afghan officials did not want to trigger a "crisis of confidence" that would happen if mass evacuations began, says Biden.

Biden says the crisis unfolding in Afghanistan is "gut-wrenching" for US veterans who fought there over the past 20 years.

For them, he says, "this is deeply deeply personal".

"It is for me as well. I've worked on these issues as long as anyone," he continues.

"From Kabul to Kandahar... I've spoken to the people. I've met with the leaders. I've spoken to our troops."

The US president says the Afghan government failed to take his advice and negotiate a political settlement with the Taliban.

“Mr Ghani insisted that the Afghan forces would fight. But obviously he was wrong.”

"I stand squarely behind my decision," Biden says.

He adds that he has "always promised the American people I would be straight with you", but admits that the situation with the Taliban's recent advance has "unfolded more quickly than we anticipated".

"Americans cannot and should not be dying and fighting in a war that Afghans are not willing to fight for themselves," he says.

Biden continues by saying that former US President Donald Trump's deal with the Taliban shrunk the US troop presence in the nation from about 15,500 to 2,500. He adds that Trump's deal with the Taliban called for US forces to leave by 1 May.

"The Taliban was at its strongest militarily since 2001," he says.

"The choice I had to make as your president was either to follow through on that agreement, or be prepared to go back to fighting the Taliban in the middle of the May fighting season."

There was no agreement after 1 May to protect US troops from the Taliban after that date, he says.

"There was never a good time to withdraw US forces," he says, adding that the country folded "quicker than anticipated".

Image source, EPA

President Biden is now speaking from the White House.

In a live televised address, he says his national security team is "closely monitoring" the situation on the ground in Afghanistan.

In the president's first remarks since the Afghan government fell to the Taliban on Sunday, he says the US mission in Afghanistan was "never supposed to be nation building," but instead was designed to prevent "a terrorist attack on US soil".

Sam Farzaneh
BBC Persian reporter

Image source, Getty Images

Washington DC police have closed Lafayette Park on the north side of the White House. The park has been the scene of angry protests against the US withdrawal since the fall of Kabul on Sunday.

The park's closure is a sign of security concerns by police and the Secret Service.

A group of Afghans are continuing to gather nearby to protest as President Biden prepares to address the nation.

The protesters who come from one of the largest Afghan communities in the DC area were here on Sunday as well.

They tell me they are just hoping “someone can hear” their concerns and do something for the people of Afghanistan.

Tara McKelvey
BBC News, Washington

The West Wing looks much as it always does, even as the crisis over Afghanistan deepens.

Copies of the Washington Post are displayed on a desk where White House assistants work.

In another area, down the hall from the Oval Office, the National Geographic is lying on top of a bookshelf.

The president has always prided himself on his international background, and as a leader in foreign policy, and National Geographic fits nicely into his reading shelf.

But there are signs that not everything is well here: the screaming headlines in the Washington Post, with dire headlines about Afghanistan, are the first hint.

Plus, the hallways are unusually crowded, as Secret Service agents and aides gather, and wait.

The president, moving on Biden time, as it is known here, plans to make remarks in the East Room, any minute now.

He will try to explain how he, an experienced foreign-policy maven, managed to misjudge in such a colossal way what has happened in Kabul, and will attempt to justify his policy decisions.

Those here in the West Wing, and in places around the world, are waiting.