Defence Minister Richard Marles says the new treaty with PNG will be signed ‘imminently’. SuppliedDefence Minister Richard Marles says the new treaty with PNG will be signed ‘imminently’. Supplied Credit: SuppliedHistory demonstrates that any attack on Papua New Guinea would always engage Australia’s national interest, Defence Minister Richard Marles said in explaining a key reason propelling the dramatic new mutual defence treaty with the close Pacific neighbour. In fact, that is our history when that has happened.”Camera Icon Australia and Papua New Guinea will soon sign a mutual defence treaty. “It is about ensuring Papua New Guinea is safe, secure, and prepared to protect its people and borders.”Camera Icon Richard Marles inspects an honour guard during the Papua New Guinea 50th Anniversary of Independence celebrations in Lae.