 If creating a new amphibious vehicle were delayed, the Marines would have to rely more on the MV-22 Osprey and other helicopters in the near-future for moving troops to a breach, which cannot support them on the ground or protect them under armor.A high-speed vehicle may not even be viable for future assault landings, as even though it would be made to deploy further out to sea to give stand-off protection of transport ships from anti-ship missiles, the ACV itself would then be vulnerable to those missiles.Methods of traveling on water are limited to current and slow methods through it or traveling on top, similar to a jet ski, which is expensive.