A lack of transparency and assurance from China about why it's rapidly building up its military is causing concern in Australia.
Australia is urging China to be more transparent about its unprecedented military build-up.
Defence force chief Angus Campbell said Australia didn't condemn any country for shoring up its own national security.
But such a large-scale increase should come with transparency and assurances to the international community.
"There has been some critique of an absence of transparency and of assurance to the region with regard to the scale and intent of that build-up," the general told a Senate hearing on Tuesday.
China's military now commands the world's largest navy with about 355 ships and 58 submarines, up from 210 at the turn of the century.
It is expected to grow to 440 by 2030.
Of the 58 submarines, 12 are nuclear and this continues to grow as older models come out of service.
"It's not the most powerful or most capable but it is a very consequential force, and it is continuing to grow," General Campbell said.
It doesn't include hundreds of extra coast guard vessels and maritime militia which can be used to carry out the interests of the Chinese Communist Party, particularly in exerting sovereignty claims in the south and east China seas.
China also has the world's third-largest air force with more than 2000 aircraft, including the latest fifth-generation fighters.
Beijing has compiled 1250 ballistic missile systems, which include highly advanced hypersonic missiles.
About 400 are nuclear-armed missiles and this is expected to increase to about 1500 by 2035 or 2040. This compared to a stagnant 150 to 200 nuclear-armed missiles two decades ago.
In space, it has expanded its capability from 16 satellites which can be used for military purposes to over 300.
General Campbell said there had been a significant change in the "technological sophistication" of China's ability across land, air, sea, space and cyber over the past two decades.
Defence department secretary Greg Moriarty said talks between Australian and Chinese officials in March had been used to express the government's views about the build-up and its consequences for regional and national security.
He said the defence force had to move quickly to shore itself up against "the largest military build-up ever seen in the Indo-Pacific".