President Joe Biden authorized an additional 1,000 US troops for deployment to Afghanistan to ensure what Biden called an “orderly and safe drawdown” of American and allied personnel.

U.S. troops will also help in the evacuation of Afghans who worked with the military during the nearly two-decade war.

From scheduled drawdown to sending troops, the decision reflects the abject security situation as Taliban capture cities.

Biden attributed much of the chaos unfolding in Afghanistan to former President Donald Trump’s efforts to end the war, which Biden said created a blueprint that put US forces in a difficult spot with an emboldened Taliban challenging the Afghan government.

“When I came to office, I inherited a deal cut by my predecessor – which he invited the Taliban to discuss at Camp David on the eve of 9/11 of 2019 – that left the Taliban in the strongest position militarily since 2001,”

In his statement Biden didn’t explain the numerical breakdown of the 5,000 troops he said had been deployed.

Initially 1,000 troops were in place to aid with the withdrawal, and administration officials quickly judged that total to be insufficient. An additional contingent of Marines arrived in Kabul as part of a 3,000-troop force intended to secure an airlift of US Embassy personnel and Afghan allies as Taliban insurgents approached the outskirts of the capital.

The additional 1,000 troops approved Saturday appeared to bring the total to 5,000.

Officials have stressed that the newly arriving troops’ mission was limited to assisting the airlift of embassy personnel and Afghan allies, and they expected to complete it by month’s end. But they might have to stay longer if the embassy is threatened by a Taliban takeover of Kabul by then.

“Clearly from their actions, it appears as if they are trying to get Kabul isolated,” Pentagon spokesman John Kirby said, referring to the Taliban’s speedy and efficient takedown of major provincial capitals this past week.

But the decision in recent days to dispatch 4,000 fresh troops suggested that American forces and their allies were at risk. There was no discussion of rejoining the war, but the number of troops needed for security will depend on decisions about keeping the embassy open and the extent of a Taliban threat to the capital in coming days.

The president said Satuday his administration had conveyed to Taliban representatives in Qatar that any actions in Afghanistan that harm U.S. personnel will be met by a “swift and strong” military response.

Biden also directed Secretary of State Antony Blinken to support Afghan President Ashraf Ghani and engage with regional leaders in the pursuit of a political settlement with the Taliban.

Despite the Taliban’s gains, the Biden administration has said that Afghan security forces’ air force and superior numbers could give them an edge against the insurgents.

The State Department said the embassy in Kabul would remain partially staffed and functioning, but Thursday’s decision to evacuate a significant number of staff suggested concerns about protecting American and Afghan lives as the Taliban progressed through the country.