WASHINGTON (AP) — President Joe Biden authorized an additional 1,000 U.S. troops for deployment to Afghanistan, raising to roughly 5,000 the number of U.S. troops 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.

The last-minute decision to re-insert thousands of U.S. troops into Afghanistan reflected the dire state of security as the Taliban seized control of multiple Afghan cities in a few short days. The militant and fundamentalist movement gained control of key parts of the country it governed until being ousted by U.S. and coalition forces after the Sept. 11 attacks. Biden had set an Aug. 31 deadline for fully withdraw combat forces before the 20th anniversary of the attacks.

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 U.S. 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," Biden said in a statement Saturday. “I was the fourth president to preside over an American troop presence in Afghanistan — two Republicans, two Democrats. I would not, and will not, pass this war onto a fifth.”

In his statement Biden didn’t explain the numerical breakdown of the 5,000 troops he said had been deployed. But a defense official said in a media statement that the president had approved Defense Secretary Lloyd Austin’s recommendation that the lead battalion of the 82nd Airborne Brigade Combat Team assist in the State Department’s drawdown.

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 U.S. 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.

In a sign of fears that the Taliban could soon capture Kabul, U.S. Embassy personnel were urgently destroying sensitive documents, according to two U.S. military officials who spoke on condition of anonymity because they were not authorized to discuss the actions.

As the situation in Afghanistan rapidly worsened, Biden, who was spending the weekend at Camp David, and Vice President Kamala Harris held a secure video conference on Saturday morning with national security officials before Biden announced the additional troops.

On Saturday, the Taliban captured Mazar-e-Sharif, a large heavily defended city in northern Afghanistan, and closed in on Kabul by taking the Logar province just to the south. The Taliban have made major advances in recent days, including capturing Herat and Kandahar, the country’s second- and third-largest cities.

“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.

Biden had given the Pentagon until Aug. 31 to complete the withdrawal of the 2,500 to 3,000 troops that were in Afghanistan when he announced in April that he would end U.S. involvement in the war. That number has dropped to just under 1,000, and all but about 650 were scheduled to be gone by the end of the month; the 650 were to remain to help protect the U.S. diplomatic presence, including with aircraft and defensive weapons at the Kabul airport.

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.

Having the Aug. 31 deadline pass with thousands of U.S. troops in the country could be problematic for Biden, who said he had no regrets about stopping the U.S. war by that date. Republicans criticized the withdrawal as a mistake and ill-planned, though there was little political appetite by either party to send fresh troops to fight the Taliban.

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.

Ghani delivered a televised speech Saturday, his first public appearance since the recent Taliban gains, and pledged not to give up the “achievements” of the 20 years since the U.S. toppled 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 statement served to highlight the lack of morale by Afghan forces to fight in a situation where the Taliban seemed to be speeding forward.

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. The Biden administration has not publicly ruled out a full embassy evacuation or possibly relocating embassy operations to the Kabul airport.