Days prior to the revelation that a new port which could be used by the US Marines was being planned on the edge of Darwin, a placard popped up on one of the city's main commuter arteries.

"No USA war base" blared the letters of the sign hanging off the Bagot Road pedestrian bridge, which neighbours land owned by Australia's Defence Department.

Other similarly slapdash carboard banners were also erected along the street.

Their appearance signalled that some within the tropical capital may have been aware of the impending news — and perhaps the rest of the region's residents shouldn't have been too surprised.

While nothing has yet been declared through official government or Defence channels, the signs of such a development have long existed.

Whether or not the NT will see more foreign boots on the ground, the ADF has been steadily improving and upgrading defence infrastructure in and around Darwin in recent years — a fact which falls somewhat contradictory to the reality that ADF numbers have been on a steady decline in Darwin for the past decade.

Secret planning has begun for a new port facility just outside Darwin which could eventually help US Marines operate more readily in the Indo-Pacific.

Precise details remain tightly guarded but senior defence and federal government figures concede the proposal may risk angering China even though it's a commercial port, not a new military base.

Multiple officials, speaking on the condition of anonymity, have confirmed to the ABC the multi-use development would be in the Glyde Point area, roughly 40 kilometres north-east of Darwin's existing port.

Darwin port, which was controversially leased to a Chinese company in 2015, has existing defence facilities such as a multi-user barge ramp, but the new proposed facility would have the additional advantages of being less busy and less visible.

If approved, the new port could eventually be able to accommodate large amphibious warships such as Australia's Landing Helicopter Docks, and American vessels such as the USS Wasp, which recently arrived in Sydney.

Strategic experts believe a new deep-water port would be ideally suited for the more than 2,000 US Marines and their equipment during regular rotations through the Top End.

"The Americans are clearly not withdrawing from the Indo-Pacific, whether it's because of their strategic competition with China or more generally," said Rory Medcalf from the Australian National University.

It's understood a formal announcement on the new maritime facility could be made as early as next month when the "Talisman Sabre" war games with the US begin in the Northern Territory and Queensland.

Ecuador’s decision to allow US planes to use a San Cristobal airfield prompts environmental concerns.

Opposition congressman Carlos Viteri said the agreement with the US was "unacceptable" and should be prohibited if "it intends to cede an inch of Ecuadorian territory".

Under Article 5 of Ecuador's constitution, the country is "a territory of peace" and the "establishment of foreign military bases or foreign facilities for military purposes shall not be allowed".

Ecuador's former president Rafael Correa also reacted angrily, tweeting (in Spanish) that the island was "not an aircraft carrier" for the Americans.

The Galapagos Islands, 563 miles (906km) west of continental Ecuador, are a Unesco World Heritage site renowned worldwide for their unique array of plants and wildlife.

A US Marine has died in a training accident at the Mt Bundey Training area after suffering injuries in a tactical vehicle accident on Saturday.

Lance Corporal Hans Sandoval-Pereyra died yesterday after succumbing to injuries suffered in the incident which saw one other marine suffer minor injuries.

He was conducting routine training at the training facility when the incident occurred and was initially treated at the scene before being medically evacuated by helicopter to Royal Darwin Hospital.

Commanding Officer for Marine Rotational Force — Darwin Colonel Russ Boyce said efforts were unsuccessful in saving the Marine’s life who was a valued member of the Marine Corps.

“We are saddened by the loss of Lance Corporal. Sandoval-Pereyra. He was a beloved member of our community and our deepest sympathies go out to his family and friends,” he said.

“We are extremely grateful to our Australian partners for their valiant efforts to save this young Marine’s life.”

The second Marine has been released from Hospital.

TWO military aircraft experienced mid-flight malfunctions over Top End skies within 24 hours of each other.

A Royal Australian Air Force spokeswoman said a C130 aircraft a USAF F-16 fighter jet were involved in separate incidents on Monday and Tuesday.

She said a C130 aircraft was returning to Darwin at 5.35pm on Monday when an engine “malfunctioned”, but the aircraft was able to land safely without incident.

The next day the USAF F-16 aircraft experienced an in-flight emergency and was forced to return to the base early ending its flight.

“The aircraft dumped fuel in accordance with normal procedures. The aircraft landed safely using the cable at approximately 9.10pm

Exercise Diamond Storm began in late April and runs until May 29 with aircraft operating out of RAAF Bases Tindal and Darwin. According to the RAAF, the exercise is the final phase of the Air Warfare Instructor Course, a three phase intensive six-month course that integrates war fighting functions across a range of specialisations.