The prime minister is in Tokyo for annual leaders' talks with his Japanese counterpart Shinzo Abe on Thursday and North Korea was set to be a key focus.
The pair visited a Japanese military base at Narashino, where they inspected the Patriot missile defence system which Japan uses to protect the Tokyo skyline.
Apache and Chinook helicopters circled overhead in a show of Japanese military might.
Prime Minister Malcolm Turnbull. Source: AAP
Japanese military commanders told Mr Turnbull that depending on the missile, it could take up to two minutes to intercept one coming from North Korea.
"You need to be quick," Mr Turnbull said.
He maintained denuclearisation of the Korean Peninsula had to be the main game.
"When the regime shows real movement in that direction, I think that's where negotiations can begin in earnest," Mr Turnbull told reporters at the base.
"We have to maintain the economic pressure from the sanctions and not to...accept a sort of a lull from North Korea as an indication that they are going to change their ways.
Mr Turnbull said he agreed with US Secretary of State Rex Tillerson that the military option should remain on the table.
Japanese Prime Minister Shinzo Abe (L) and Australian Prime Minister Malcolm Turnbull (R) talk during their meeting on November 13, 2017 in Manila, Philippines. Source: Getty
Australia and Japan are pushing for closer defence ties and will later in 2018 sign a defence agreement that will provide a legal framework for more joint military exercises.
Under the deal Japanese troops could conduct military exercises out of Darwin - almost 76 years after Japanese planes bombed the city in World War II.
Mr Turnbull and Mr Abe sat inside a blast-resistant military vehicle called the Bushmaster which Thales makes in Bendigo, Victoria.
Mr Abe was behind the steering wheel while Mr Turnbull chatted beside him in the passenger's seat and they waved at the cameras.
The Australian military has used the vehicles in Iraq and Afghanistan and 100 had been involved in improvised explosive device attacks but there have been no lives lost.
Japan has already purchased four Bushmasters and four more have been ordered - representing Canberra's biggest defence export to Tokyo.
Trade and investment are also a key focus of the trip.
Mr Turnbull is confident the Trans-Pacific Partnership trade pact can be finalised by March, when trade ministers from the 11 countries meet in Chile.
The agreement was thrust into limbo when President Donald Trump withdrew the US.
Canada delayed efforts to seal the deal late last year.
"There are hills and hollows as you go along to get to the goal," he said.
Both Mr Abe and Mr Turnbull have both been "energetic advocates" of the agreement.
