The United States military is preparing to spend more than a quarter of a billion dollars on naval construction in the Northern Territory, in a move that could raise tensions with China.

the Defence Department says it is still too early to comment on what the US military may have planned in the Northern Territory.

"The referenced document is the Senate version of the National Defense Authorization Act, which authorises (but does not appropriate) Defence initiatives," the Department said in a statement.

"It is still progressing through the US Congress and must be reconciled with the House version before it is finalised. It is not yet approved.

"We expect the US Department of Defense will provide details of the funding in accordance with its processes and timelines following consideration and approval within the United States Government."

The draft US legislation also outlines several other proposed spending projects in the Northern Territory including $US50 million for a "new airport parking apron for the Navy", and $US70.6 million for the Air Force at Tindall.