The AUKUS announcement has fuelled more speculation about possible expansion of the marines' presence in the Top End, which Defence Minister Peter Dutton has already said he would like to see.
In an interview with the ABC, the USA's Charges d'Affaires in Australia, Michael Goldman, said talks on the subject were ongoing.
Michael Shoebridge, the director of defence, strategy and national security at the Australian Strategic Policy Institute, said northern Australia was becoming another staging point for US personnel, logistics and resources in the Asia Pacific.
Under the 2011 agreement, marines will keep returning to Darwin each dry season for 25 years, ending in 2036. The USA Charges d'Affaires, said the deployments were "just a beginning rather than an end" of the US presence in Australia.