Amphibious invasion without a major port

Would a US amphibious invasion still need to secure a major port, or could equipment come over the beach?

It depends on retaining heavy amphibious ships and logistics systems; without them, a force will need access to a major port or must seize one without its own heavy equipment.

A force can move heavy equipment across a beach only if it retains LPDs, LHDs, landing craft, and the wider logistics system built around them. Discarding those ships assumes that a functioning major port will always be available. If the port instead has to be seized, an army without heavy ship-to-shore lift faces the circular problem of capturing it before its own heavy equipment can land. Amphibious operations have recurred from Korea and Suez through later decades, even though the long intervals between crises make the requirement easy to forget.