Changes in NAT mapping

1) When the initiator detects a change in its NAT mapping (from a received
NAT_DETECTION_DESTINATION_IP payload), it does not actually know what the new
mapping is, and hence, following Sec. 3.5, does nothing to change its IKE_SA,
correct? It only sends UPDATE_SA_ADDRESSES to tell the peer to update its SAs' 
tunnel endpoints.


2) Can other INFORMATIONAL exchanges be used to detect changes in NAT mapping?
Sec 3.8 seems to imply only the IKE_SA_INIT exchange and exchanges containing
UPDATE_SA_ADDRESSES should be used.