President Joe Biden has decided to withdraw all U.S. forces from Afghanistan by the end of August, bringing an end to America’s longest war sooner than a previous plan. But a Republican lawmaker called the decision a “disaster in the making.”

“Our military mission in Afghanistan will conclude on August 31st,” Biden announced in a speech at the White House on Thursday, July 8.

“The drawdown is proceeding in a secure and orderly way, prioritizing the safety of our troops as they depart,” he added.

Biden said his administration is on track to meet the drawdown target set earlier this year when it eyed Sept. 11 as the deadline for a complete pullout from Afghanistan.

Biden revealed that his military commanders advised him to move swiftly once he decided to end the war because conducting the drawdown differently would have certainly come with an increased risk of safety to personnel.

“I want to be clear: The U.S. military mission in Afghanistan continues through the end of August.  We remain—we retain personnel and capacities in the country, and we maintain some authority—excuse me, the same authority under which we’ve been operating for some time,” he said.

“As I said in April, the United States did what we went to do in Afghanistan: to get the terrorists who attacked us on 9/11 and to deliver justice to Osama Bin Laden, and to degrade the terrorist threat to keep Afghanistan from becoming a base from which attacks could be continued against the United States. We achieved those objectives. That’s why we went,” he continued.

Biden said that the U.S. troops did not go to Afghanistan to nation-build, and “it’s the right and the responsibility of the Afghan people alone to decide their future and how they want to run their country.” 

Biden announced the complete troop withdrawal after the Pentagon said the removal is 90% complete. The U.S. Central Command said that it has transferred more than 17,000 pieces of military equipment for disposition and transferred seven facilities over to the Afghan forces.

The new drawdown deadline comes as the Taliban is gaining control of new territory at an alarming pace, according to USA Today.

However, Biden defended his decision to withdraw the troops, telling reporters it was not inevitable the Taliban would seize control of the Afghan government and that he trusts the Afghan National and Defense Security Forces.

“The Afghan troops have 300,000 well-equipped—as well-equipped as any army in the world—and an air force against something like 75,000 Taliban.  It is not inevitable,” Biden told reporters in the Q&A.

“Do I trust the Taliban?  No. But I trust the capacity of the Afghan military, who is better trained, better equipped, and more re—more competent in terms of conducting war,” Biden said.

Following Biden’s remarks, Sen. Lindsey Graham (R-S.C.) released a series of tweets, saying the decision to remove all U.S. troops from Afghanistan would “prove to be his biggest mistake yet.”

“President Biden does not understand conditions are developing in Afghanistan for a reemergence of al-Qaeda and ISIS which will directly threaten the American homeland and our allies,” Graham wrote. “Get ready for major upheaval as this decision by President Biden is a disaster in the making.”

In a follow-up tweet, the Republican senator said that “President Biden has learned nothing from their Iraq withdrawal debacle. That decision led to the rise of ISIS.”

“It is important to remember that President Biden’s Afghanistan decision to withdraw all forces was made against sound military advice—just like he and President Obama did in Iraq,” he tweeted.

“President Biden may have set a deadline to end the war with al-Qaeda and ISIS in Afghanistan. Unfortunately for us, al-Qaeda and ISIS don’t have deadlines when it comes to attacking American interests,” he wrote in another tweet. 

“When it comes to understanding the war on terror and the dynamics we face as a nation, President Biden has consistently been wrong. I fear that his Afghanistan decision will prove to be his biggest mistake yet,” Graham added.

Under his administration, President Donald Trump reached an agreement with the Taliban. The U.S. agreed to pull its forces from Afghanistan, and the Taliban promised to sever its ties with al-Qaida and end its attacks on American forces.