The full text of the deal was tabled in Papua New Guinea's parliament on Wednesday evening and obtained by AFP, shedding light on details that have been closely guarded since the pact was inked in May.

With Papua New Guinea's agreement, the United States will be able to station troops and vessels at key airports, as well as sites such as the Lombrum naval base on Manus Island and a seaport in the capital Port Moresby.

Washington would have "unimpeded access" to the sites to "pre-position equipment, supplies and materiel", and have "exclusive use" of some base zones where "construction activities" could be carried out.

Prime Minister James Marape has been forced to defend the deal against a wave of protests and criticism, with some opponents questioning whether Papua New Guinea was signing away its sovereignty.

"We have allowed our military to be eroded in the last 48 years," he told parliament on Wednesday evening. "Sovereignty is defined by the robustness and strength of your military."

Rich in natural resources and close to key shipping routes, Papua New Guinea increasingly finds itself at the centre of a diplomatic tug-of-war between Washington and Beijing.

Former prime minister Peter O'Neill said the agreement painted a target on Papua New Guinea's back.

"America is doing it for the protection of their own national interest, we all understand the geopolitics happening within our region," he said.