The major announcement will not involve any US boots on the ground in the Palestinian enclave, as military personnel will stay offshore while other allies are involved, officials said.

"Tonight the president will announce in his State of the Union address that he has directed the US military to undertake an emergency mission to establish a port in Gaza," a senior administration official told reporters.

"This port, the main feature of which is a temporary pier, will provide the capacity for hundreds of additional truckloads of assistance each day," the official said on condition of anonymity.

US officials said the "significant capability will take a number of weeks to plan and execute," and would involve a maritime corridor bringing aid by sea from the Mediterranean island of Cyprus.

US officials were careful to stress that American troops would not be on the ground in Gaza, which has been under relentless Israeli bombardment since the October 7 Hamas attacks on Israel.

A second official said it was "foreseen to be an operation that won't require boots on the ground."

"The US military has unique capabilities. And they can do things from just offshore that are extraordinary and so that is the concept of operations that the president has been briefed on," the official said.

The Israelis had been informed and the US would work with them on security requirements while coordinating with "partners and allies" and UN and aid organizations on the ground.

The announcement during the key State of the Union speech underscores the acute political pressure Biden is under for his steadfast support for Israel, despite the mounting Gaza death toll and humanitarian crisis.

Biden announced last week that the US was beginning airdrops of aid to Gaza, following an incident in which more than 100 people were killed at an aid station in the north of the territory.