Defence Minister Richard Marles was hosted by his Japanese counterpart Nobuo Kishi in Tokyo on Wednesday where the pair spoke about closer defence ties and a "step-up sophistication of exercises and activities".

In January, the countries formally signed what is known as a "reciprocal access agreement", setting up the rules around defence cooperation including training and disaster support.

"(The agreement) opens the door for a whole lot of engagement and opportunity between Japan and Australia that we have not had before," Mr Marles told reporters in Tokyo.

"Much greater engagement in terms of activities, much greater engagement in terms of interoperability.

"Today's meeting really sought to put the meat on the bones of that. To put forward a substantive agenda, an ambitious agenda around how we can use the reciprocal access agreement to transform our relationship."

Mr Marles described the relationship with Japan as "front and centre in terms of our national interest".

"When I was growing up in the 1980s what was at the heart of the Australian-Japanese relationship was essentially commerce," he said.

"That's still there but what has become clear is, in the last decade, the building of our defence and security relationship is very much at the heart of the work we're doing together."

Australia and Japan are also working in a tripartite partnership with the United States as China continues to become more aggressive in the region.

The three defence ministers met at the sidelines of a regional security conference in Singapore over the weekend.

"We want to take the relationship with Japan forward. We want to be working as closely as we can with Japan and we particularly want to do that in connection with the United States as well," Mr Marles said.

"It's really clear that when times are tough, friends come to the fore."

Mr Marles says Australia's proximity and partnerships with Pacific nations enables it to take a lead role with Japan in the region, as Tokyo expands its engagement in the Indo-Pacific.

Japanese infrastructure projects in the Pacific would build relationships in the region and enhance Canberra and Tokyo's joint capabilities, Mr Marles added.

"There are fantastic infrastructure projects today that have been delivered by Japan in the Pacific, which bring great reputation ... and that's something we need to be building."

Japan will send aircraft to participate in Exercise Pitch Black in the Northern Territory for the first time in August.

Australian Associated Press