The United States will send its largest aircraft deployment to Australia as part of the next rotation of Marines to Darwin in coming months.

About 1,250 US Marines are due to arrive in Darwin in April as part of a six-month rotation.

Although the number of Marines was originally expected to jump to 2,500 in 2016-17, efforts by the US Marine Corps to rein in spending were reportedly behind a move to keep the number at the same as during the last deployment.

The arrival of the planes will, however, constitute the largest deployment of US aircraft here.

It will include four tilt-rotor Ospreys, five Super Cobra helicopters and four Huey helicopters.

This compares with the four UH-1Y helicopters sent for the rotational deployment in 2016 and four CH-53E Super Stallions in 2015.

US military newspaper Stars and Stripes cited Marine Corps Forces Pacific executive director Craig Whelden as saying the deployment represented a "more diversified" and "more capable force" than previous ones.

"The United States has used Australia as a base for many decades and in many different respects, whether it is cyber security information gathering, the marines in Darwin and the air force," Defence Industry Minister Christopher Pyne said.

"Australia has real capability in maintaining and sustaining our own aircraft and American aircraft. The Americans know that if they send their aircraft to Australia and they need to be maintained or sustained in some particular way, it can be done here."

In October, Australia and the US agreed to a cost-sharing agreement for more than $2 billion worth of infrastructure spending in northern Australia and ongoing costs of the rotations over the 25-year life of the agreement.

The rotations of US Marines to Darwin was first announced by former prime minister Julia Gillard and former US president Barack Obama in 2011 as part of America's military's long-term "pivot" to the Asia-Pacific region.