KABUL, Afghanistan (AP) — In his three combat tours in Afghanistan, Gen. Mark Milley saw the Taliban as a formidable foe, one unlikely to “fade away in the dust,” as he put it in 2013. This week, Milley, now chairman of the Joint Chiefs of Staff, sat across a negotiating table with leaders of the group that seemed defeated after the U.S. invaded in 2001 but will remain a force even as the U.S. sends troops home.

Milley held an unannounced meeting with Taliban leaders in Doha, Qatar, to discuss military aspects of last February’s U.S.-Taliban agreement, which was intended to set the stage for direct peace talks between the Taliban and the Afghan government.

He then flew to Kabul to consult with Afghan President Ashraf Ghani. Milley said he emphasized to both parties the need to rapidly reduce levels of violence.

“Everything else hinges on that,” he told reporters from The Associated Press and two other news organizations.

Although Milley reported no breakthrough, his Taliban meetings represent a remarkable milestone — America’s top general coming face-to-face with representatives of the group that ruled Afghanistan until it was ousted 19 years ago this month in the early stages of what became America’s longest war.

Milley served his first tour in Afghanistan as a brigade commander with the 10th Mountain Division in 2003, returned five years later as a deputy commander of the 101st Airborne Division, and then served as head of the international coalition's Joint Command in Kabul from May 2013 to February 2014.

The U.S. invasion of Afghanistan in October 2001 was aimed at overthrowing the Taliban regime, running al-Qaida out of the country and laying the groundwork for a global “war on terrorism.” It turned into something more ambitious but less well-defined and became far more costly in blood and treasure.

Milley believes the United States still has an important national interest in Afghanistan, where al-Qaida militants plotted the Sept. 11, 2001, attacks. But it's unclear — probably to him and to the Taliban as well — how Joe Biden as president will approach the evolving Afghan-Taliban peace process. Milley is in the second year of a four-year term as Joint Chiefs chairman and is likely to be a source of military continuity as the Biden administration settles in.

Biden has not said publicly whether he will continue the drawdown or how he will proceed with the February agreement negotiated by Trump’s peace envoy, Zalmay Khalilzad.

In that agreement, the Taliban agreed to renounce al-Qaida and take other steps to enhance peace prospects, while the Trump administration agreed to reduce its troops — reaching a complete U.S. withdrawal by May 2021. Washington, however, has complained that violence levels are too high.

In his talks with the Taliban on Tuesday, Milley urged a reduction in violence across Afghanistan, as senior American officials in Kabul warned that stepped-up Taliban attacks endanger the militant group's nascent peace negotiations with the Afghan government.

“The most important part of the discussions that I had with both the Taliban and the government of Afghanistan was the need for an immediate reduction in violence,” Milley said in an interview.

Under ground rules set by Milley for security reasons, the journalists traveling with him agreed not to report on his talks until he had departed the region. It was Milley's second unannounced meeting with the Taliban's negotiating team; the first, in June, also in Doha, had not been reported until now.

Army Gen. Scott Miller, the top commander of U.S. and coalition forces in Afghanistan, said in an interview at his military headquarters in Kabul on Wednesday that the Taliban have stepped up attacks on Afghan forces, particularly in the southern provinces of Helmand and Kandahar, and against roadways and other infrastructure.

“My assessment is, it puts the peace process at risk — the higher the violence, the higher the risk,” Miller said. He meets at least once a month with Taliban negotiators as part of Washington's effort to advance the peace process.

Speaking in the same interview, Ross Wilson, the ranking American diplomat in Kabul, said he also sees growing risk from Taliban violence. He said it has created “an unbearable burden” on the Afghan armed forces and the society as a whole.

Miller said he was saddened by what he called the Taliban's deliberate campaign to damage roadways, bridges and other infrastructure as part of an effort to limit the Afghan government's ability to reinforce its troops.

“Military commanders on the ground are now starting to do things that are not conducive to peace talks and reconstruction and stability,” Miller said. “Clearly, the Taliban use violence as leverage” against the Afghan government.

Miller said he is executing Trump's order to reduce U.S. forces from 4,500 to 2,500 by Jan. 15, just days before Biden is sworn in as Trump's successor. Miller said troop levels are now at about 4,000 and will reach the 2,500 target on time.

As the troops pull out, some U.S. military equipment will be given to the Afghans, some will be sent to the United States, and some will be destroyed, Miller said.

Biden has not laid out a detailed plan for Afghanistan but has made clear he prefers a small U.S. military footprint and limited goals. He has acknowledged that he dissented from then-President Barack Obama’s decision in December 2009 to vastly increase troop levels in hope of forcing the Taliban to the peace table.

“I think we should only have troops there to make sure that it’s impossible for... ISIS or al-Qaida to re-establish a foothold there,” Biden told CBS News in February.