The introduction of Mobile IP functionality for end users in 3G has no influence on the security architecture for 3G.
Mobile IP terminals may be equipped with security functionality independent of the 3G network access security in order to allow security functions outside the 3G network.
3G networks, supporting Mobile IP services, should support its inherent security functionality.
On the other hand, 3G network access security architecture can not be influenced or reduced by the Mobile IP option.
The Mobile IP security functionality must thus be separate from the 3G network access security and it is developed in an other forum, IETF.