The RAAF has secured a $10 billion deal with the US to replace ageing Hercules aircraft. 

The US State Department has approved the “possible foreign military sale” of 24 C-130J-30 planes and related equipment, which are expected to replace the RAAF's existing fleet of 12 Hercules aircraft.

The $10 billion purchase was made without a formal tender, and despite an ongoing review of significant military spending ordered by the Albanese government.

“This proposed sale will support the foreign policy and national security objectives of the United States,” the US Defense Security Cooperation Agency (DSCA) says.

“Australia is one of our most important allies in the Western Pacific,” the DSCA added.

The RAAF has been using the Lockheed Martin-made C-130 Hercules since 1958. Australia's current fleet entered service more than 20 years ago.

“The strategic location of this political and economic power contributes significantly to ensuring peace and economic stability in the region,” the DSCA said.

“It is vital to the US national interest to assist our ally in developing and maintaining a strong and ready self-defense capability.”

The Defence Department claims to have thoroughly examined other international options for replacing the ageing C-130 fleet.

“Defence has identified that the new C-130J aircraft represents the only option that meets all of Australia's capability requirements and assures Defence's medium air mobility capability without introducing substantial cost, schedule and capability risk,” it said. 

Lockheed Martin re-signed a multi-year deal with Sydney-based defence company Quickstep last year to produce wing flaps as part of the international C-130J production supply chain.