7News Spotlight on Sunday investigates how critical defence infrastructure is alarmingly exposed.

What happens around a warship docked at a major tourist hotspot will shock viewers and raise urgent questions about our national security.

The investigation spans key military sites including Pine Gap, Williamtown RAAF Base, Amberley RAAF Base and Garden Island Naval Base, where billions of dollars in defence assets are housed.

What's exposed are weaknesses in the protection of critical weapons systems: F-35A stealth fighters stored under shade cloth and naval ships and our most important air bases subject to easy intrusion.

Liam Bartlett said: "We found billion-dollar fighter jets stored under shade cloth, warships exposed to drones, and critical bases protected by little more than cyclone fencing. These are critical gaps in our defence capability at a time when our adversaries and neighbours are investing like never before."

Speaking to 7NEWS Spotlight, former Chief of Army Peter Leahy, alongside key military experts and industry insiders, warn that Australia's defence policy may be woefully inadequate for the real-world threats we face.

Lieutenant General (ret) Peter Leahy told Liam Bartlett: "This peace is fast coming to a close, so we better be ready for war. And I don't think we're ready."

Bartlett also travels to the Philippines, to witness how other nations are standing up to China's military aggression now, while Australia's defence plan will not see us combat ready until at least 2030.

Liam Bartlett said: "Our investigation shows that while the threats are evolving rapidly, Australia's response is stuck in slow motion. We're investing in submarines we won't see for a decade, while our current defences are exposed and under-equipped."

In the Philippines, Bartlett catches up with Defence Minister Richard Marles, who has been dodging 7NEW Spotlight's questions for months, to discuss a policy experts say is all words and no action.

"You don't want to be known as minister for show bags," Bartlett said. "There has to be substance to it."