At which the self-proclaimed and illegitimate state “Islamic State in Iraq and Syria” is involved. This is far more dangerous than just to Americans and the United States’ Afghani allies—this is now also unequivocally dangerous to Americans and American allies (including—like their Afghani counterparts—Assyrian Christians in Iraq among other people) in ethnoreligious minority groups in the Middle East (which Afghanistan borders at its border with Iran):

“ISIS prompted US Embassy to issue security threat to Americans headed to Kabul airport

A threat from the Islamic State’s branch in Afghanistan prompted a security threat from the U.S. embassy in the country that told American citizens to avoid traveling to the airport. 

“There are other terrorists groups we are concerned about as well,” one defense official said. The official declined to give details, but the Pentagon has said that “hundreds” of al-Qaeda fighters are in Afghanistan. 

The U.S. embassy in Afghanistan warned Saturday: "Because of potential security threats outside the gates at the Kabul airport, we are advising U.S. citizens to avoid traveling to the airport and to avoid airport gates at this time unless you receive individual instructions from a U.S. government representative to do so." 
Posted by Fox News“