WASHINGTON (Reuters) - President Joe Biden is expected to announce on Friday his intention to order a military air drop of humanitarian aid into Gaza, four U.S. officials told Reuters, speaking on condition of anonymity.

The officials declined to discuss exact timing of the expected U.S. air drop of aid into Gaza, although two officials said it could happen in the coming days.

At least 576,000 people in the Gaza Strip - one quarter of the enclave's population - are one step away from famine, according to the U.N. Office for the Coordination of Humanitarian Affairs.

A humanitarian disaster is unfolding in the Gaza Strip, particularly the north, after nearly five months of an Israeli air and ground campaign that has ruined swathes of the crowded coastal strip and pushed it to the edge of famine.

With people eating animal feed and even cactuses to survive, and with medics saying children are dying in hospitals from malnutrition and dehydration, the U.N. has said it faces "overwhelming obstacles" getting in aid.

David Deptula, a retired U.S. Air Force three-star general who once commanded the no-fly zone over northern Iraq, said air drops are something the U.S. military can effectively execute.

"It is something that's right up their mission alley," Deptula told Reuters.

"There are a lot of detailed challenges. But there's nothing insurmountable."

(Reporting by Phil Stewart, Idrees Ali and Nandita Bose; Editing by Chris Reese and Rami Ayyub)