"DF-27 intermediate-range ballistic missile, and potentially a conventionally armed intercontinental ballistic missile, grow in service numbers" [DF-27]
The DF-27's expanding inventory, combined with a potential conventionally armed ICBM, directly names the missile proliferation mechanism by which strike reach extends to continental Australia.
Reasoning from this article
The article treats Australia's exposure as an instance of a broader structural shift: long-range precision weapons are collapsing the geographic insulation that separated major-power conflict zones from distant allies. The same dynamic applies to any nation previously shielded by distance — the DF-27's 5,000–8,000km range is the specific technical threshold that makes this a general pattern, not an Australia-specific anomaly. Island-basing in the South China Sea further extends forward reach, compounding the missile range effect. This generalizes to any Indo-Pacific state outside traditional threat corridors now finding itself within the engagement envelope of a modernizing PLA.