By Jennifer Hansler, CNN

(CNN) -- Secretary of State Antony Blinken arrived in Kabul, Afghanistan, Thursday in an unannounced visit to the country where US troops have been fighting for nearly 20 years.

Blinken touched down in the Afghan capital less than 24 hours after the United States and the NATO coalition formally announced they would withdraw their troops from the country after nearly two decades.

In remarks alongside Afghan political leaders, Blinken attempted to underscore that although the US military presence on the ground was drawing to a close, its commitment to the people and the country would remain.

On Wednesday, President Joe Biden announced that all US troops would begin to withdraw by May 1 -- the deadline set out in the deal the Trump administration signed with the Taliban last year -- and would be gone by September 11 -- the 20th anniversary of the deadly terrorist attack on US soil that set into motion America's longest running war.

While meeting with Afghan President Ashraf Ghani, the top US diplomat said he "wanted to demonstrate, with my visit, the ongoing commitment of the United States to the Islamic Republic and the people of Afghanistan."

Ghani said that he respected the US decision and that Afghanistan was "adjusting our priorities."

Blinken also met with Dr. Abdullah Abdullah, the chairman of the Chairman of the High Council for National Reconciliation and told him that they "have a partnership that is changing, but is enduring."

"As the President said, we have a new chapter, but it's a new chapter that we're writing together," he said. "The top US diplomat said he "was very eager to come as quickly as possible also to begin the important work we have in writing that new chapter."

Abdullah thanked Blinken for his "continued commitment in support of peace."

Prior to those meetings, Blinken addressed American troops at the US embassy and thanked them for their service.

"I know this is a moment for many of mixed emotions. These are hard choices, hard decisions," he told them.

"The reason I'm here so quickly after the President's speech last night is to demonstrate literally, by our presence, that we have an enduring, an ongoing commitment to Afghanistan," Blinken said, according to the press pool accompanying him. "What you and your predecessors did over the last 20 years is really extraordinary."

The top US diplomat also met with members of Afghan civil society, mostly women, at the US Embassy, according to the pool.

In remarks at NATO headquarters in Brussels Wednesday, Blinken said the US would "continue support for the rights of Afghan women and girls, minorities advocating for their meaningful participation in the ongoing negotiations and their equal representation throughout society, and we'll maintain significant humanitarian assistance to those in need."

Despite those commitments, many analysts have voiced concerns that the announcement of a full US troop withdrawal will hamper the ongoing intra-Afghan negotiations and that leaving the country without a durable settlement in place could risk the gains made by civil society and women.

According to a US intelligence community assessment, "prospects for a peace deal will remain low during the next year."

"The Taliban is likely to make gains on the battlefield, and the Afghan Government will struggle to hold the Taliban at bay if the coalition withdraws support," the assessment said.

On Wednesday, Blinken did not dispute that assessment, but noted that Biden took it into consideration and still determined that it was in the best interests of the United States to withdraw.

"I would say the Taliban has a choice to make. They say that they want international recognition, that they want international support. They're part of Afghanistan's governance. Of course, there are a number of other things that they want, including prisoner releases and delistings and so forth. And those things will, I think, will be significantly affected by the path that the Taliban chooses to take going forward," Blinken said in Brussels.

"In addition, I think it's in no one's interest, including the Taliban's, to plunge Afghanistan back into a long war, into a civil war that will do terrible damage to the country and to everyone," he said. "So I think the assessment, again, is a realistic one, but there are, I think, a whole series of incentives and disincentives that will continue to shape what happens."

"But ultimately, the people of Afghanistan will be the ones to decide their future. We will do everything we can to support efforts toward a peaceful, stable, just future, but they're the ones who have to decide," he said.

This story has been updated with additional information.