Why is SRB 1 used for RRC connection reconfiguration message transfer

Specs & Protocol Testing
1

Hi friends.
As mentioned SRB used to transfer RRC and NAS message.
I have 1 doubt: why SRB 1 used for RRC connection reconfiguration message transfer?
Why not SRB 2?
As I can see content of RRC connection reconfiguration having SRB 2 IE definition.

2

3 posts were merged into an existing topic: Why SRB2 if SRB1 itself is capable of transfering NAS messages?