Top U.S. general in Afghanistan steps down as military mission nears end

General Scott Miller stepped down today as both the last and longest serving American commander in America's longest war. At a small ceremony at Resolute Support headquarters in Kabul, Afghanistan, Miller called the assignment "the highlight of my military career," saying the people of Afghanistan "will be in my heart and on my mind for the rest of my life."

His departure marks the symbolic end of the 20-year U.S. military mission in Afghanistan. And it comes amid a surge in violence from Taliban militants who have launched coordinated offensives across the country.

Miller said he told Taliban representatives, "It's important that military sides set the conditions for a peaceful and political settlement in Afghanistan, but we know that with that violence, it would be very difficult to achieve a political settlement."

Miller has been in charge of U.S. and NATO forces since 2018, a role that will now be led from afar — from CENTCOM headquarters in Tampa, to be exact.

Central Command Marine General Frank McKenzie made the trip to Kabul for the handover ceremony. As CENTCOM commander, McKenzie already had authority over Afghanistan and much of the rest of the region, including Iraq and Syria.

On the flight to Kabul, McKenzie told a group of reporters that he believed the Taliban are pursuing a "military victory" over the Afghan government, as evidenced by the insurgent group's rapid battlefield gains in recent weeks.

The Taliban have taken control of more than one-third of Afghanistan's 421 districts, seizing several strategic locations including border crossings with Iran, Tajikistan and Uzbekistan.

Afghan defense officials tell CBS News government forces have been consolidating around provincial capitals, setting the stage for a military showdown with Taliban fighters.

"I think, certainly, the provincial capitals are at risk and we'll see how that shakes out over the next few weeks," McKenzie said. "I think the Afghans are determined to fight very hard for those provincial capitals."

McKenzie retains the authorization to order air strikes against the Taliban in support of Afghan government forces at least through the completion of the U.S. military withdrawal by August 31. After that, McKenzie says he will focus U.S. firepower on operations against al-Qaeda and ISIS in Afghanistan.

But he admitted that most of the intelligence the U.S. military relies on from the battlefield comes from Afghan forces themselves, and losing those eyes and ears is going to impact future military operations.

"That's just a fact we're going to have to recognize," McKenzie said. "My knowledge of what's going on in Afghanistan is not nearly what it was 180 days ago."

In Kabul, the task of completing what's left of the U.S. military pullout and transitioning to the next phase falls to Rear Admiral Peter Vasely. That includes command over around 650 U.S. forces to protect the U.S. embassy and an unspecified number to help bolster security at Karzai International Airport along with a Turkish military contingent of 500 soldiers.

The challenges ahead are many as the last of the U.S. troops leave in the few weeks ahead of the August 31st deadline.

The Taliban have said they consider any remaining foreign forces as "invaders" and therefore legitimate targets, raising questions about the U.S. troops that will guard the embassy and the airport after the deadline passes.

Then there is unresolved issue of more than 18,000 Afghan interpreters who served with the U.S. military and their families who are desperate to flee the country in fear of being targeted by the Taliban.

In his farewell speech, General Miller said "our job now is not to forget" those who have sacrificed here. 

But with the Taliban more powerful than ever and the country facing a volatile future, Americans may wonder what that sacrifice was for.