A US military serviceman in the Northern Territory has tested positive for COVID-19 after arriving to join the Marine Rotational Force in Darwin.
The 22-year-old was diagnosed with the virus on Wednesday after arriving in the Top End on an international flight on Monday.
The Marine has been placed in isolation at the Howard Springs quarantine centre and has mild symptoms, an NT Health spokeswoman said on Thursday.
About 2200 marines will arrive in Darwin by June in batches of 200-500 servicemen and women.
It's the 10th Marine Rotational Force to train with the Australian Defence Force.
Former defence minister Linda Reynolds previously said all US personnel would undergo COVID-19 testing within 72 hours of departure for Australia and must present a negative result before boarding their flight.
They are also required to complete mandatory 14-day quarantine with virus testing on arrival in Australia and again before leaving the quarantine facility.
The Marines have rented a secure facility outside Darwin - understood to be Bladin Point, about 20km south of Darwin - for the majority of personnel to complete their quarantining.
The total number of coronavirus cases diagnosed in the NT is 114. All cases have been related to international or interstate travel, with no cases of community transmission.