NATO is leaving the door open for a larger security force in Afghanistan than initially planned after 2016.

But officials say the alliance is waiting for the U.S. to announce its decision, which could come as soon as next week.

NATO secretary-general Jens Stoltenberg says decisions will be made based on a detailed security assessment that will determine the size of the force, where they will be based and how long they will stay. He predicted a decision in the coming weeks, but other officials suggested President Barack Obama could make his plans known fairly soon.

The top U.S. military commander in Afghanistan, Gen. John Campbell told Congress this week that he has recommended Obama revise his plan and keep more than 1,000 troops in the country beyond 2016.