What RRC message does eNodeB send to UE when it detects a radio link failure?

In the case of the eNodeB detecting a radio link failure, what RRC message does it send to a UE. If it is an RRCConnectionRelease, how can we determine the cause is a radio link failure, since the releaseCause doesnt specify that case.

The eNB can send a PDCCH Order or a Intra-Cell HO to force the UE to regain UL sync. If it fails, then it will result ultimately in a RLF. If it works, UE is no longer UL out-of-sync.