Almost 700 people on 25 boats have been turned back since the start of Operation Sovereign Borders.
Immigration Minister Peter Dutton, in an update on the operation on Thursday, said that it had been 600 days since the last asylum-seeker boat arrival.
"The government is as resolute as we've ever been in staring down the continuing threat from people smugglers," he told reporters in Canberra.
The head of Operation Sovereign Borders, Major General Andrew Bottrell, said people-smuggling networks in the region had been "severely degraded".
"Even though those networks have been degraded ... there are still occasional tests of our settings and of our deterrence framework," he said.
In February a group of people was returned to Sri Lanka and in early March a group was returned to Indonesia.
General Bottrell said work with other countries in the region had foiled 57 people-smuggling ventures, resulting in 1900 people not getting onto boats.
