The present disclosure provides a method performed by user equipment, user equipment, and a handover command generation method. The method performed by user equipment includes: receiving a handover command including a handover condition, and storing a handover configuration in the handover command, wherein when the handover condition is met, the user equipment performs the handover configuration corresponding to the handover condition; and if a master cell group (MCG) failure is detected or if it is detected that a security update needs to be performed, performing at least an operation related to the stored handover configuration. Therefore, user equipment can determine the validity of a handover command, thereby avoiding a service interruption caused by a connection failure resulting from a handover performed on the basis of an invalid handover command.