Australia is to acquire eight new Poseidon maritime surveillance aircraft, able to watch over a vast area of ocean and if necessary attack enemy ships and submarines.
But Prime Minister Tony Abbott doubts they will have a role in stopping the flow of asylum seeker boats.
"We expect the first one to be in operational service by 2017 and I think the boats will be stopped by then," he told reporters in Canberra.
Under the $4 billion deal, the RAAF will replace its 19 elderly Lockheed AP-3C Orion aircraft with the Boeing P-8A Poseidon, a design based on the widely used Boeing 737-800 airliner. There's an option for four more.
Poseidons are now entering service with the US and Indian navies.
They can be equipped with Harpoon missiles to attack ships and torpedoes and depth charges to attack submarines. They can also conduct search and rescue missions. Onboard systems will give Poseidon a very advanced electronic surveillance and intelligence-gathering capability.
After inspecting a US Navy Poseidon at Canberra airport, Mr Abbott acknowledged these were a long time coming.
In 2007, the former coalition government gave initial approval to acquire Poseidon. Australia subsequently contributed $150 million to join the P-8A development program, later adding a further $100 million.
In Australian service, the new Poseidons will eventually operate in conjunction with proposed Triton unmanned surveillance aircraft in a $7 billion upgrade to maritime surveillance capabilities.
As a new aircraft, the Poseidon has experienced problems, with the Pentagon last month deeming US Navy Poseidons ineffective at their primary jobs of reconnaissance and submarine hunting because of problems with the radar and other systems.
However, Mr Abbott said he understood these difficulties had been resolved and the aircraft would be further upgraded.
He said these advanced aircraft were needed because Australia's economic zone comprised four per cent of the world's oceans and the search and rescue zone 11 per cent.
"It's an enormous part of the Earth that we are required to supervise and if necessary control and these aircraft are going to be a very important part of our capacity to do that in the decades to come," he said.
Defence Minister David Johnston said this was a cutting edge capability which would replace Orions which had been in RAAF service since the late 1960s.
"This a phenomenal strategic capability for Australia," he said.
RAAF chief Air Marshal Geoff Brown said this was the world's most advanced maritime surveillance aircraft and a worthy successor to the Orions.
"The P-8 gives us an unprecedented capability to find, fix and track both surface ships and submarines," he said.
