With Afghan President Hamid Karzai refusing to sign a security pact with Washington to allow US troops to stay after 2014, there was no prospect NATO could reach such an accord either, alliance head Anders Fogh Rasmussen said.
"Without the necessary legal framework, there simply cannot be a deployment after 2014," Rasmussen said.
"So today, we agreed the need to plan for all possible outcomes. Including the possibility that we may not be able to deploy to Afghanistan after 2014, due to the persistent delays we have seen," he said.
"However, it might be the unfortunate outcome if there is no security agreement in due time. This is what is at stake."
More From This Section
Earlier this week, US President Barack Obama talked by phone to Karzai over his repeated refusal to sign the Bilateral Security Agreement with Washington.
The BSA lays deal the legal basis for a continued US and NATO troop presence in the form of a training mission post-2014.
It is expected to number up to 12,000 troops, mostly American, and is seen as an important guarantee of continued US and NATO support during a difficult transition period.