"Seeing the arrest of five people who wanted to cause harm to the Australian community is what we joined for," said Commander John Tanti of the Australian Federal Police.
Mr Tanti spoke at a press conference announcing the seizure of 77 kgs of heroin, the biggest seizure in WA's history.
It is alleged that the Australian Border Force (ABF) found the heroin in a consignment of industrial kitchen equipment which arrived from Malaysia.
Commander James Copeman of the Australian Border force said when the crates arrived, they went through an x-ray.
"The crates were x-rayed and officers found anomalies in two of the three crates," Mr Copeman said.
Inside one of the crates was an industrial oven, which was carefully deconstructed by law enforcement officers.
"Officers subsequently discovered 132 blocks of suspected narcotics."
A small sample was taken from the blocks, and received a presumptive positive test for heroin.
WA Police commander Tony Longhorn said this seizure would lead to a much bigger investigation.
"The investigation does not stop with the driver of the car, the passenger of the vehicle or someone manning a warehouse," Mr Longhorn said.
"We will now pursue the trafficker and the criminal network who coordinated and were going to distribute this illicit commodity within the community of Western Australia.
"Make no mistake - this was destined for the streets."
On June 1, intelligence agencies and law enforcement worked closely together and substituted the heroin before executing a controlled delivery of the consignment to a Warehouse in Bibra Lake.
"Officers patiently waited and watched the property until two men were seen entering the warehouse on Tuesday and leaving with black dufflebags," Mr Tanti said.
"Police intercepted two vehicles arriving in convoy and arrested four men for attempting to possess border controlled drugs."