The fate of 164 suspected terrorists who have lived for years in legal limbo at Guantanamo Bay may hinge on a law that could expire if US troops withdraw from Afghanistan in 2014.

President Barack Obama has long promised to close the detention camp at a US Navy base in Cuba, and Congress is struggling with whether to ease restrictions on trials and transfers for the suspects.

A 2001 law that allowed the US military to invade Afghanistan to pursue and punish extremists linked to the Sept. 11 attacks also authorizes the Guantanamo detentions.

Whether it will remain valid if troops withdraw from Afghanistan — which Obama is considering for the end of 2014 — is an open legal question that officials and experts say must be resolved.