CNBC's Shep Smith reports the U.S. embassy is advising American citizens to leave and not travel to the airport in Kabul. Seth Jones. For access to live and exclusive video from CNBC subscribe to CNBC PRO: https://cnb.cx/2NGeIvi Secretary of State Antony Blinken said Wednesday that there may be as many as 1,500 Americans in Afghanistan left to evacuate, a calculation that he described as “difficult to pin down with absolute precision at any given moment.” Blinken said during a press conference that the U.S. currently is “aggressively reaching out” to about 1,000 contacts “multiple times a day, through multiple channels of communication” to determine if they still want to leave and to give them instructions on how to do so. However, the ultimate number might be lower, Blinken said. Blinken added that the State Department has been in direct contact with 500 other Americans in the last 24 hours with instructions on how to safely travel to the airport for evacuation. “The U.S. government does not track Americans’ movements when they travel around the world,” Blinken explained. “There could be other Americans in Afghanistan who never enrolled with the embassy, who ignored public evacuation notices and have not yet identified themselves.” “We’ve also found that many people who contact us and identify themselves as American citizens, including by filling out and submitting repatriation assistance forms, are not, in fact, U.S. citizens, something that can take some time to verify. And some Americans may choose to stay in Afghanistan,” the nation’s top diplomat said. The U.S. Embassy in Afghanistan early on Thursday issued a security alert on its website urging Americans to avoid traveling to Kabul airport and warned some at certain gates to “leave immediately.” “U.S. citizens who are at the Abbey Gate, East Gate, or North Gate now should leave immediately.” the alert said. A State Department spokesperson called it a “dynamic and volatile security environment.” White House press secretary Jen Psaki said Wednesday that many of the 1,000 contacts the U.S. is trying to reach are dual citizens who may not want to leave the country. “Maybe they have extended family there, maybe they’ve spent their entire lives in Afghanistan and they’re not yet ready to depart,” Psaki told reporters during a press briefing. “Maybe they’re working on a range of projects there and aren’t yet ready to leave them. I know that’s hard for us to understand as we’re looking at the images, but for many of these Afghans, this is their home.” Blinken’s press conference, his first since the collapse of the Afghan government to the Taliban more than a week ago, comes as U.S. and coalition forces intensify emergency evacuation flights. In the past 24 hours, Western forces evacuated 19,000 people out of Kabul on 90 military cargo aircraft flights, a cadence of one departure flight every 39 minutes, according to the Pentagon. Since the mass evacuations began Aug. 14, approximately 82,300 people have been airlifted out of Afghanistan. About 87,900 people have been evacuated since the end of July, including about 4,500 U.S. citizens and their families. The Pentagon said Wednesday that 10,000 people are currently at Hamid Karzai International Airport in Kabul awaiting a flight. About 5,400 U.S. servicemembers are assisting with evacuation efforts, with nearly 200 U.S. military aircraft dedicated to the mission. President Joe Biden on Tuesday reiterated to leaders of the G-7, NATO, United Nations and European Union that the United States will withdraw its military from Afghanistan by the end of the month. The president warned that staying longer in Afghanistan carries serious risks for foreign troops and civilians. Biden said that ISIS-K, an Afghanistan-based affiliate of the terror group, presents a growing threat to the airport. » Subscribe to CNBC TV: https://cnb.cx/SubscribeCNBCtelevision » Subscribe to CNBC: https://cnb.cx/SubscribeCNBC » Subscribe to CNBC Classic: https://cnb.cx/SubscribeCNBCclassic Turn to CNBC TV for the latest stock market news and analysis. From market futures to live price updates CNBC is the leader in business news worldwide. The News with Shepard Smith is CNBC’s daily news podcast providing deep, non-partisan coverage and perspective on the day’s most important stories. Available to listen by 8:30pm ET / 5:30pm PT daily beginning September 30: https://www.cnbc.com/2020/09/29/the-news-with-shepard-smith-podcast.html?__source=youtube%7Cshepsmith%7Cpodcast Connect with CNBC News Online Get the latest news: http://www.cnbc.com/ Follow CNBC on LinkedIn: https://cnb.cx/LinkedInCNBC Follow CNBC News on Facebook: https://cnb.cx/LikeCNBC Follow CNBC News on Twitter: https://cnb.cx/FollowCNBC Follow CNBC News on Instagram: https://cnb.cx/InstagramCNBC https://www.cnbc.com/select/best-credit-cards/ #CNBC #CNBCTV