WASHINGTON (NYTIMES) - US negotiators are trying to extract assurances from the Taleban that they will not attack the US Embassy in Kabul if the extremist group takes over the country's government and ever wants to receive foreign aid, three American officials said.

The effort, led by Zalmay Khalilzad, the chief US envoy in talks with the Taleban, seeks to stave off a full evacuation of the embassy as they rapidly seize cities across Afghanistan.

On Thursday, the State Department announced it was sending home an unspecified number of the 1,400 Americans stationed at the embassy and drawing down to what the agency's spokesman, Ned Price, described as a "core diplomatic presence" in Kabul.

The embassy also urged Americans who were not working for the US government to immediately leave Afghanistan on commercial flights.

The Taleban's march has put embassies in Kabul on high alert for a surge of violence in coming months, or even weeks, and forced consulates and other diplomatic missions in the country to shut down.

US diplomats are trying to determine how soon they may need to fully evacuate the embassy should the Taleban prove to be more bent on destruction than a detente.

"Let me be very clear about this: The embassy remains open," Price said on Thursday (Aug 12). "And we plan to continue our diplomatic work in Afghanistan."

Price said the heightened pace of the Taleban's rout, leading to increased violence and instability across Afghanistan, was of "grave concern."

"So, given the situation on the ground, this is a prudent step," he said.

Five current and former officials described the mood inside the embassy as increasingly tense and worried, and diplomats at the State Department's headquarters in Washington noted a sense of depression at the specter of closing it, nearly 20 years after US Marines reclaimed the burned-out building in December 2001.

Several people gloomily revived a comparison that all wanted to avoid: the fall of Saigon in 1975, when Americans stationed at the US Embassy were evacuated from a rooftop by helicopter.

The fears underscore what was unfathomable just a few years ago, when thousands of US forces were in Afghanistan and the US Embassy in Kabul hosted one of the largest diplomatic staffs in the world.

Khalilzad is hoping to convince Taleban leaders that the embassy must remain open, and secure, if the group hopes to receive US financial aid and other assistance as part of a future Afghan government.

The Taleban leadership has said it wants to be seen as a legitimate steward of the country, and is seeking relations with other global powers, including Russia and China, in part to receive economic support.

Two officials confirmed Khalilzad's efforts, which have not been previously reported, on condition of anonymity to discuss the delicate negotiations. A third official said on Thursday that the Taleban would forfeit any legitimacy - and, in turn, foreign aid - if it attacked Kabul or took over Afghanistan's government by force.

Other governments are also warning the Taleban that they will not receive aid if they overrun the Afghan government, given the rampage its fighters have waged across the country in recent days.

On Thursday, Foreign Minister Heiko Maas of Germany said Berlin would not give the Taleban any financial support if they ultimately rule Afghanistan with a hard-line Islamic law.

In other posts around the world, US diplomats said they were closely watching the perilous situation in Kabul to see how the State Department would balance its long-standing commitment to stabilising Afghanistan against protecting the Americans who remain there as military forces withdraw.

Ronald E. Neumann, who was the US ambassador to Afghanistan from 2005-07, described a push and pull between the Pentagon and the State Department in similar situations, given the military's responsibility for carrying out evacuations and diplomats' duty to maintain US assistance and influence even in danger zones.

"If the military goes too early, it may be unnecessary, and it may cost you a lot politically," said Neumann, who is now the president of the American Academy of Diplomacy in Washington. "If the diplomats wait too late, it looks like Saigon off the roof or the departure from Mogadishu after everything was already lost, and it puts the military people at risk. So there's no guaranteed right side."

Another senior US official expressed alarm this week at the fall of the provincial capitals across Afghanistan, and said that if other cities follow, particularly Mazar-e-Sharif, the only major northern city still under government control, the situation could disintegrate quickly.

Officials in Washington and Kabul said the embassy was holding regular meetings of an emergency action committee, which is set up in every US diplomatic post to assess whether or how soon an evacuation may be necessary. The content of the meetings is classified because, in part, they review intelligence about specific attack scenarios.

Representatives from the State Department headquarters in Washington and the US Embassy in Kabul would not discuss how often the committee was meeting, but other officials said its members were holding discussions daily.

The committee can only make recommendations, and it would be up to the embassy's top-ranking diplomat - in this case, Ross Wilson, the charge d'affaires in Kabul - to order an evacuation after consulting with senior officials in Washington.

On Thursday, Wilson warned the Taleban that "attempts to monopolise power through violence, fear and war will only lead to international isolation."

Starting in April, the embassy began sending home nonessential employees as security became more untenable in Kabul. Other staff members have been allowed to leave, without penalty to their careers, if they feel in danger.

One diplomat said a number of what he described as small military elements have recently been brought in to reinforce the embassy, which is inside what is probably already the most hardened compound in Kabul's international zone, where diplomatic missions and the Afghan government are based.

At the same time, officials said, fewer diplomats are rotating into Kabul to replace colleagues who have left to further cull the number of Americans posted there. That has raised concerns in the US diplomatic corps that the embassy would have trouble recruiting staff for years to come.

"It's a wrenching time," said Eric Rubin, president of the union that represents career foreign service officers and who is a former ambassador to Bulgaria. He said about one-quarter of the current US diplomatic corps have been posted to either Afghanistan or Iraq over the past 20 years and remain emotionally invested in the war zones in which they worked.

"There was a lot of sacrifice," Rubin said. "Everyone who served there for the most part served without their families, and under difficult conditions; at times under mortar fire. So it wasn't easy."

As recently as last month, senior officials at the embassy in Kabul voiced confidence that personnel there could be evacuated quickly if necessary, noting a sufficient number of commercial flights leaving from the capital's international airport every day could accommodate the compound's staff.

It is not clear, however, whether an evacuation would include all of the embassy's foreign personnel along with US citizens, and the fate of Afghan employees who would all but certainly be targeted by the Taleban for aiding the United States is of acute concern to senior officials, according to several people familiar with the discussions.

Officials also said the Biden administration is concerned that an evacuation of the US Embassy could create a domino effect that accelerates the departure of other diplomatic missions and international support - and, in turn, leads to the collapse of the Afghan government.

"I am quite sure that no one in our Foreign Service who's involved in this effort is advocating closing down the embassy and evacuating," Rubin said.

While decisions about the embassy's security are on the horizon, he said, "there's no reason to think that there's an imminent security threat to our people."

"The first thing is, obviously, the mission, and the mission is changing," Rubin said. "But I don't think anybody's going to propose to walk away."