A master RAN node (1) associated with a master RAT (1) communicates with a secondary RAN node (2) associated with a secondary RAT and provides a radio terminal (3) with dual connectivity that uses the master RAT and the secondary RAT. In response to receiving, from the radio terminal (3) or a core network (4), terminal capability information indicating that the radio terminal (3) supports the split bearer, the master RAN node (1) uses a PDCP entity, which provides unified PDCP functionalities, for a master cell group split bearer for the radio terminal (3).