The US Navy’s attack submarine force had been predicted to reduce to 49 in 2030.

There are signs that it is shrinking faster than anticipated and the possibility that the growing workload demanded by the top priority, Columbia class ballistic missile submarines and the shift to the 31% larger Block V Virginia class could cause it to drop below earlier predictions.

The AUKUS plan requiring the sale of 3-5 Virginia class submarines would exacerbate this. Alternatively, if the submarines are not sold, Australia faces a loss of its submarine capability. The current AUKUS Pillar 1 plan is, therefore, now a threat to both the US and Australia’s submarine capabilities.

A Congressional Research Service Report issued on 28 March 2025 advised that at the end of FY2024 the US Navy had 49 operational attack submarines and forecast a decline to 47 in around FY2030. The reduction to 47 has now been reached. There are delays in commissioning new Virginia class submarines, which are taking longer to build; for example, the latest SSN 795, USS Iowa, was commissioned in April this year, 40 months late on the contracted date. Meanwhile, the ageing Los Angeles class retire as their hull and/or reactor life expires. Predicting the delivery of new submarines and demise of the old is not a precise art, variations may occur to the number and timing.

The source for the number of attack submarines is the US Navy’s official website, which advises that some submarines undergoing inactivation may be included in the 47, implying that the number of operational submarines is actually less.

Delays to maintenance of in-service submarines are further reducing the number available for deployment.

Current moves to recover slippage and accelerate the Columbia class ballistic missile construction program and a shift to construction of a larger version of the Virginia probably means further delays and shrinkage – if so, the number of operational attack submarines has yet to bottom out.

I can envisage a scenario where the USN SSN force could be reduced to 41 or less by 2032.

This assumes that the remaining 4 Block IV Virginia class submarines under construction commission six years after they were laid down and the three currently laid down Block V submarines commission eight years after they were laid down. If so, in January 2032 there will be seven new SSNs to add to this number. This estimate could prove optimistic; we have yet to see how long it will take the overtaxed shipyards and supply chains to build the Block V.

It is unlikely to be pessimistic; it is hard to envisage submarines not yet laid down being commissioned in this timescale.

On the negative side of the ledger; retirement of the Los Angeles class continues faster than they can be replaced. Assuming the seven life-extended submarines are still operational, (although the youngest will be 36 years old), the Navy loses 13 of these submarines. It could be better, more may be suitable for extension, but it is also quite likely to be worse as old submarines have a habit of springing surprises! Let’s assume the USS Seawolf will still be operational, although it will be 35 years old and approaching retirement.

Faced with the reality of shrinking/ageing SSN force and delivery of replacement submarines delayed behind the higher priority Columbia and slower build rate of the larger Virginias, the decision due in 2031 on whether to sell Australia three to five frontline SSNs should be easy. Can the US spare three frontline Virginias from the 31 in service? The answer will be: “Sorry, we have none to spare.”

Delivering new submarines has been made more difficult by an uptick in the Columbia program cadence; the US’ top priority is to build 12 new, Columbia class, 20,810 tonne ballistic missile submarines. The first two have been laid down several years apart in 2021 and 2024, to ease the load on the building yards.

From 2026, until 2035, the tempo increases to one laid down each year – a huge extra load on the building yards, not to mention the space required for a production line of seven to eight of these very large submarines.

These problems will be compounded by an increase in the size and complexity of the Virginia class submarines being built. Once the remaining four Block IV, 7800-tonne submarines currently under construction are delivered, production will shift to the 10,200 tonne Block V version. This is 31% larger and has been estimated to require 25% more man-hours to construct given its increased complexity. Ten of these larger versions are on order, only three have been laid down. They are to be followed by three Block VI submarines of a similar size and complexity.

The new target, encompassing a Columbia each year and two of the larger Virginias, would require at least a three-fold increase in submarine construction tonnage compared with annual average build of 1.14 smaller versions of the Virginia actually achieved over the last 21 years. Compared to the US Navy’s target of delivering two Virginias each year over this period, that is a cumulative shortfall of 18 SSNs.

Adding the requirement to build additional submarines to replace those to be sold to Australia would require more than a four-fold increase in construction yard output measured by tonnage. These submarines have not been laid down and the yards are fully committed hence; these submarines are many years away from commissioning.

Even if this increased output is achieved, there will predictably be no Virginias to spare for Australia due to the shortfall in USN numbers. In the final analysis, the USN remains well short of its target of 66 attack submarines; it has 47 or less now and is heading towards 41 or less in my estimate. It will be this shortfall in numbers that will be the deciding factor.

As the Congressional Budget Office recently concluded, selling three to five submarines would translate to a loss of many operational years for the US before this capability could be replaced.

In these circumstances, Australian payments of millions of dollars to support the US industrial base is justifiably being questioned.

With luck, the current Pentagon review of AUKUS will reach this obvious conclusion and withdraw from this plan. Failing that, we will continue until reality hits, when the next president declares the US national interest outweighs the “best endeavours” we are now relying on.

The US’ submarine building challenge is a serious risk to the current AUKUS “optimum pathway”, since the sale of three to five Virginia class submarines to cover the gap between the demise of the Collins class and arrival of the new, British-designed SSN AUKUS is highly unlikely to occur.

That gap is likely to be longer than expected as delays to SSN AUKUS, which depends on Britain’s capacity to design and build two new classes of nuclear-powered submarines, are highly likely. Britain’s submarine capability is in a mess, a situation which I will discuss in a second piece.

It is time the AUKUS partners recognised the realities and changed their plan in response.

The views expressed in this article may or may not reflect those of Pearls and Irritations.