Approval has been given for the first phase of the $500 million redevelopment of the Australian War Memorial in Canberra.
The National Capital Authority has given the nod for early works including the demolition of Anzac Hall.
The NCA had asked for further information on tree removal and replacement planting, noting that there were 595 trees in the precinct.
"A total of 455 trees are to be retained, while 140 trees are to be removed as part of the project," the NCA's chairman Terry Weber said in a statement on Monday.
"The NCA will require that the AWM plant a minimum of an additional 250 native trees as a condition of approval for these works.
"With this change noted, the NCA has concluded the proposal is not inconsistent with the National Capital Plan and the works have been approved."
The NCA, which has published a 1200-page consultation report, received 601 submissions during its consultation process, of which three were in support.
Key concerns were the need for the expansion, tree removal, the impacts on heritage values and the cost.
The AWM argues the project will address constraints to the existing use of the building, improve the overall visitor and veterans' experience and maintain its significance as a national cultural institution.
"The current Anzac Hall is a bespoke building that is not extendable and is no longer fit for purpose to meet the memorial's needs to tell the stories of recent conflicts," it said.
"New galleries created will provide the space needed to share the experiences of Australians who have served in conflict and operations in places including Somalia, Rwanda, Cambodia, Solomon Islands, East Timor, Iraq, Afghanistan and Syria."