A method for supporting handling of change of serving Access and Mobility Management Function for a user equipment, wherein said method is performed at a target Access and Mobility Management Function and comprises: - sending of, from the target Access and Mobility Management Function, a security context request to a source Access and Mobility Management Function; - receiving of, in said target Access and Mobility Management Function, a security context in reply from the source Access and Mobility Management Function, wherein said security context comprises a parameter which identifies a Security Anchor Function Access and Mobility Managing Function, said Security Anchor Function Access and Mobility Management Function being an Access and Mobility Management Function that keeps a key denoted Kseaf and serves as a root key for derivation of core network and access network keys and is shared with said user equipment and has resulted from a primary authentication procedure for network access between the user equipment and an authentication server function via the Security Anchor Function Access and Mobility Management Function; - identifying the Security Anchor Function Access and Mobility Managing Function using the parameter, and - deciding an authentication strategy based on a security policy depending on the location of said source Access and Mobility Management Function and said identified Security Anchor Function Access and Mobility Management Function, wherein the authentication strategy comprises one of: an execution of a new authentication procedure, and a request from the target Access and Mobility Management Function of a new core network key derived from the Kseaf to said Security Anchor Function Access and Mobility Management Function. - sending of, from the target Access and Mobility Management Function, a security context request to a source Access and Mobility Management Function; - receiving of, in said target Access and Mobility Management Function, a security context in reply from the source Access and Mobility Management Function, wherein said security context comprises a parameter which identifies a Security Anchor Function Access and Mobility Managing Function, said Security Anchor Function Access and Mobility Management Function being an Access and Mobility Management Function that keeps a key denoted Kseaf and serves as a root key for derivation of core network and access network keys and is shared with said user equipment and has resulted from a primary authentication procedure for network access between the user equipment and an authentication server function via the Security Anchor Function Access and Mobility Management Function; - identifying the Security Anchor Function Access and Mobility Managing Function using the parameter, and - identifying the Security Anchor Function Access and Mobility Managing Function using the parameter, and - deciding an authentication strategy based on a security policy depending on the location of said source Access and Mobility Management Function and said identified Security Anchor Function Access and Mobility Management Function, wherein the authentication strategy comprises one of: an execution of a new authentication procedure, and a request from the target Access and Mobility Management Function of a new core network key derived from the Kseaf to said Security Anchor Function Access and Mobility Management Function. an execution of a new authentication procedure, and a request from the target Access and Mobility Management Function of a new core network key derived from the Kseaf to said Security Anchor Function Access and Mobility Management Function.