The federal Greens oppose the expansion of the Australian War Memorial and launched a policy that would share the half-a-billion dollars earmarked for the project across all of Canberra's national institutions.

As part of a broader defence and foreign aid policy announcement on Friday, the party also said the war memorial should be banned from accepting donations from weapons manufacturers but should receive more government funding to make up the shortfall.

Greens leader Richard Di Natale says the War Memorial expansion shouldn't go ahead. Credit:AAP

Greens leader Richard Di Natale made the promise on Friday along with a commitment to reduce Australia's spend on defence and end the alliance with the United States.

Both the Liberal government and the Labor party have committed to support the War Memorial in its $498 million expansion, but the Greens say it wouldn't be necessary if its halls weren't filled with military hardware.