According to some examples, a base station may allocate uplink and/or downlink resources (e.g., in the time domain, frequency domain, spatial domain) to user equipment (UEs), or groups of UEs, that may be subsequently reallocated. For example, a base station may determine a reallocation of uplink resources, and may issue a preemption indication (e.g., a cancelation indication) that may correspond to at least a portion of a random access resource. UEs may be configured to monitor for preemption indications and, based on received preemption indications, UEs may determine whether or not to proceed with transmission of a random access message using a random access resource that at least partially overlaps with resources indicated by the preemption indication. For example, a UE may transmit, or preempt transmission of, a random access message based on a preemption configuration of the UE (e.g., configured rules for UE preemption of random access resources).