Question: During an ongoing NAS Security Mode Command (SMC) procedure to take a new KASME into use, how should the MME handle AS security context parameters in HANDOVER REQUEST or PATH SWITCH REQUEST ACKNOWLEDGE messages?
Option 1: Immediately include AS security context parameters based on the new KASME.
Option 2: Continue to include AS security context parameters based on the old KASME until a UE Context Modification procedure takes a KeNB derived from the new KASME into use.
Option 3: Randomly alternate between including AS security context parameters based on the old and new KASME.
Option 4: Omit AS security context parameters altogether during this period.
Explanation: This maintains consistency and avoids mismatches between security contexts in the network and the UE during concurrent security procedures. Continuing with the old KASME's AS security context parameters ensures seamless handovers until the new KASME is fully integrated through a UE Context Modification procedure.