Australia and Papua New Guinea on Monday signed a major mutual defense treaty seen as mainly intended to offset China’s expanding military clout in the South Pacific and prevent Beijing from projecting power through Australia’s northern approach.

The deal, which will elevate the long-standing relationship to a formal alliance, was signed by Australian Prime Minister Anthony Albanese and his Papua New Guinea counterpart, James Marape, in Canberra after the Papua New Guinea Cabinet formally approved the landmark deal last week.

Known as the Pukpuk Treaty, in reference to the Papua New Guinean pidgin word for "crocodile," the pact was initially set to be signed on Sept. 17 alongside celebrations for Papua New Guinea’s 50th anniversary of independence from Australia. However, the two countries issued only a joint communique at that time, as the Papua New Guinea Cabinet lacked the required quorum.