WASHINGTON (Reuters) -U.S. embassy staff in Kabul were leaving the compound and moving to the airport, Secretary of State Antony Blinken said on Sunday, as Taliban insurgents entered the Afghan capital and officials said President Ashraf Ghani had left the country. There were reports of sporadic gunfire around the city, but there was no significant fighting and the Taliban said they were waiting for the Western-backed government to surrender peacefully. U.S. diplomats were being ferried by helicopter to the airport, where U.S. troops were providing security amid an exodus of Americans and their local allies and other foreigners. Sources told Reuters that most U.S. staff would be evacuated from Kabul in the coming day or two. We're working to make sure that our personnel are safe and secure. We're relocating the men and women of our embassy to a location at the airport, Blinken told ABC news. More U.S. forces had been sent in to get U.S. officials out of the country in a safe and orderly fashion while maintaining a core diplomatic presence, Blinken said. France, Germany, the Netherlands and Sweden all said on Sunday they were moving their diplomats from their embassies. A NATO official said the group was maintaining its diplomatic presence in Kabul and helping to keep the airport running. 'NOT SAIGON' A U.S. intelligence assessment earlier in the week had said Kabul could be encircled in 30 days and could fall to the Taliban within 90 days, but the insurgents captured most of Afghanistan's major cities in less than a week and entered the capital on Sunday. Some 4,200 people remained in the U.S. embassy until Thursday, when the Taliban's rapid gains forced the Biden administration to begin flying in thousands of troops to help pull many of the remaining diplomats out. The State Department insisted at the time the embassy was not closing, but by Sunday sources said almost all U.S. personnel would be pulled out of the country within a day or two. U.S. officials have said they do not expect the military strategy in Afghanistan to change as long as the Taliban allow evacuations to continue. Asked if the evacuation was evocative of the U.S. departure from Vietnam in 1975, Blinken told ABC news: “Let's take a step back. This is manifestly not Saigon.” Washington invested billions of dollars over four U.S. administrations in Afghan government forces, giving them advantages over the Taliban, but they were unable to defend the country in the face of the militants' advance, Blinken told CNN. That has happened more quickly than we anticipated, Blinken said. The United States' original mission in Afghanistan, launched to oust al Qaeda chief Osama bin Laden after the Sept. 11, 2001, attacks, had been fulfilled, Blinken said, saying Washington had prevented further attacks by militants harbored by the Taliban. But U.S. President Joe Biden has faced rising domestic criticism after sticking to his plan to withdraw, which was agreed under his Republican predecessor Donald Trump. Republican lawmaker Michael McCaul said on Sunday a Taliban takeover would revive the threat to the United States. We are going to go back to a pre-9/11 state. A breeding ground for terrorism, he told CNN. (Reporting by Idrees Ali, Jonathan Landay, Chris Sanders, Michael Martina and Brad Heath; writing by Simon Lewis; Editing by Sonya Hepinstall and Daniel Wallis)