Australia needs to build a missile defence shield, says former national security adviser Andrew Shearer

Some news reports say North Korea has identified the Australian city of Darwin as a target because US Marines are using it as a training hub. Photo / 123RF

Australia needs to build a missile defence shield to protect overseas forces and the mainland, a former national security adviser has warned.

Rising tensions with North Korea underscore the need for Australia to "get much more serious" about defence, according to Andrew Shearer, a leading defence specialist who worked for former prime ministers Tony Abbott and John Howard.

"The problem is that North Korean - and Chinese - missile development has been accelerating very rapidly, particularly over the past few years, to the extent it has often taken Western analysts by surprise," Mr Shearer, who is based at the Centre for Strategic and International Studies in Washington, told Fairfax Media.

He continued: "The cumulative effective of these capabilities is to increase the missile threat to ADF forces deployed forward in the [Asia] region - whether independently or as part of an allied coalition - but also, over time, to reduce Australia's strategic depth and put Australian and allied forces operating from rear bases on the mainland at greater risk. The latter is a new threat but one that will become very real over the next decade."

He said Australia had to "get much more serious, potentially quite quickly given the looming North Korea threat, about missile defence for deployed forces."

He said this means planners need to investigate systems "to defend the continent against the new and growing threat posed by long-range ballistic missiles that could be used to strike or intimidate future Australian governments."

The warning comes after North Korea last week accused Australia of "blindly and zealously toeing the US line" and threatened a nuclear strike.

"If Australia persists in following the US moves to isolate and stifle the DPRK and remains a shock brigade of the US master, this will be a suicidal act of coming within the range of the nuclear strike of the strategic force of the DPRK," a foreign ministry spokesman said, according to North Korea's state-run KCNA news agency.

Foreign Minister Julie Bishop hit back, saying North Korea's threats "present a grave threat to its neighbours, and if left unchecked, to the broader region including Australia."

Overnight, Ms Bishop ramped up her condemnation of the rogue nation, saying it violated UN Security Council resolutions on numerous occasions.

Speaking on Wednesday in Tallinn, Estonia, Ms Bishop said North Korea has disregarded international law and is "causing great tension in our region, that's why Australia and others have called North Korea to change its behaviour".

Amid rising tensions between North Korea and South Korea and the United States, Australia wants "to see a denuclearised Korean Peninsula", she added.

The Turnbull government has said North Korea does not currently have nuclear weapons capable of reaching Australia.

However, some news reports say North Korea has identified the Australian city of Darwin as a target because US Marines are using it as a training hub.