In an interview with the BBC's HARDtalk overnight, Minister Turnbull said the measures are needed to end the people smuggling trade.
"We have measures, some would say they're cruel measures.
"I would say they're harsh, I wouldn't go so far as to say they're cruel. Let's not argue about semantics. The fact is if you want to stop the people smuggling business you have to be very, very tough."
Mr Turnbull said the government's controversial Operation Sovereign Borders complied with international law.
"I don't think any of us are entirely comfortable with any policies relating to border protection.
"We have harsh measures (and) some would say they are cruel measures.
"(But) the fact is if you want to stop the people smuggling business you have be very, very tough."
Mr Turnbull said former prime minister Kevin Rudd had conducted a "massive social science experiment" when he closed offshore detention centres, resulting in a huge increase in boat arrivals and subsequent drownings at sea.
"It's been a catastrophe," he said.
