With China’s armed forces growing bigger and more sophisticated by the year, Western and allied militaries are scrambling to keep up.

The Australian military for one has a plan for taking the fight to China. As part of a $400 billion defense-wide plan stretching out to 2030, the Royal Australian Air Force intends to arm its growing fleet of American-made fighters with long-range cruise missiles.

Farther in the future, additional support planes could further bolster the fighters.

But the tyranny of distance—Australia lies more than a thousand miles from any likely battle zone—imposes hard limits on Canberra’s ability to wage aerial warfare against a distant enemy. Every mile an air package must travel in order to reach the fight decreases its endurance in battle and increases its reliance on tankers and early-warning planes.

And those support planes are in short supply.

For all the billions of dollars that Canberra plans to spend on its air force in coming years, it still could struggle to significantly expand its capacity for long-range, high-intensity aerial combat.

With its planned fleet of 72 F-35A and 24 F/A-18F fighters, the RAAF could keep just two jets on station with Joint Air-to-Surface Stand-Off Missiles or Long-Range Anti-Ship Missiles, which can range as far as 300 miles and 230 miles, respectively. The missile radiuses are in red on the map.

The reason for this hard limit on combat capacity is not that the air force lacks fighters. Even taking into account training and maintenance demands, the RAAF in theory could deploy dozens of F-35s and F/A-18s. But both types can fly just 300 miles or so with weapons and internal fuel.

Traveling farther than that requires aerial-refueling. And the RAAF has just seven KC-30 tankers. A section of two fighters, sustained by six additional fighters and flying a theoretical maximum of 930 miles from the air base at Darwin, also would need support from an E-7 early-warning plane. The RAAF has just six of those. The E-7s of course could need their own tanker support.

“The biggest stressor on the viability of the mission is tanker capacity,” the Australian Strategic Policy Institute explained in 2019. “It’s hard to see more than five [KC-30s] being available, and fewer will be serviceable on any given day. One tanker, engaged in continuously refueling fighters on the combat air patrol, can’t stay on station for more than four to six hours before needing to refuel.”

“Sustaining two refueling stations (one to get the fighters out to the patrol area and one to sustain them on station) with a force of only four or five tankers would likely exceed any responsible commander’s risk tolerance by creating a single catastrophic point of failure,” ASPI continued. “One unserviceable tanker, accident or combat loss would cause the entire cycle to collapse, potentially with pilots and aircraft unable to make it home.”

To put it another way, the RAAF’s entire support force—the tankers and early-warning planes—is adequate to keep just a pair of fighters over the maritime choke-points around Indonesia, The Philippines and Singapore.

Absent a significant deployment of U.S. or allied tankers or access to foreign bases, the rest of the fighter force would be limited to short-range defensive patrols around Australia’s periphery—the yellow line on the map. Adding cruise missiles doesn’t necessarily alter this dynamic.

But it’s worth noting that, in the out-years of Canberra’s strategic plan, the air force plans to buy new tankers. “New investment will include larger replacement fleets,” the government stated. Doubling the tanker fleet might allow the air force to keep four fighters on station instead of just two.