"The price for leaving too soon or in an uncoordinated way could be very high. Afghanistan risks becoming once again a platform for international terrorists to plan and organise attacks on our homelands. And ISIS could rebuild in Afghanistan the terror caliphate it lost in Syria and Iraq", Stoltenberg's statement read.
On Monday, CNN cited sources as saying that US President Donald Trump is preparing to issue a formal order, as early as this week, to begin the further withdrawal of US troops from Afghanistan.
US Senate Majority Leader Mitch McConnell issued a statement late on Monday also warning of the consequences of a premature exit from Afghanistan.
Earlier in November, then-Secretary of Defence Mark Esper issued a classified memo to the White House warning against a rapid withdrawal from Afghanistan. Esper has since been dismissed from his post by the president.
Trump in early October posted a tweet saying that US troops in Afghanistan should be home by Christmas, although senior US lawmakers subsequently said that there were no such plans in the works.
Roughly 4,500 US armed forces personnel are currently stationed in Afghanistan.
* Daesh (ISIL/ISIS/IS/Islamic State) is a terrorist organisation banned in Russia