So lo and behold, the Navy and Marines have decided that they really can allow amphibious warships to approach to within 12 miles of the shore (from my Jane's email updates):
The US Navy (USN) and the US Marine Corps (USMC) have revised the minimum stand-off distance from a contested shore for amphibious operations from a minimum of 25 n miles to 12. The change is due to improvements in the USN's mine countermeasure (MCM) capability and early success of the E-2D Advanced Hawkeye carrier-based information, surveillance and reconnaissance (ISR) aircraft, Chief of Naval Operations Admiral Gary Roughead said on 2 March [2011.]
Entirely coincidental, I'm sure. I'm just not sure whether there was never a need to stay over the horizon or whether this change is to avoid having someone say that the Navy can't support a Marine amphibious mission against opposition without the EFV, so why bother funding such a capability?
I suppose it is always possible that the stated reasons for moving the safe stand-off range closer to shore are true.