Does Every Sub Need Tomahawks?

Here is a companion piece to the recent post, “Does Every Ship Need A Helicopter?” which examined US Navy design assumptions.  This time, we’ll take a look at submarine design.

One of the seeming absolute characteristics of a US Navy submarine design is the capability to shoot Tomahawk cruise missiles.  Here are the recent submarine classes and their possible Tomahawk loads.

Los Angeles  12

Ohio SSGN    154

Seawolf      50

Virginia     12-40

Without a doubt, having the capability to covertly shoot Tomahawks from submarines is a useful capability.  But, does every sub need to be able to shoot Tomahawks?

The question is not whether Tomahawk cruise missiles are useful but whether their usefulness is sufficient to justify the expenditure of ship’s volume, the concomitant increase in cost and the resulting decrease in number of submarines built?  The volume and money dedicated to a submarine cruise missile capability could go to other ship’s functions and to building more subs.  In other words, there is an opportunity cost associated with submarine launched cruise missiles.

Let’s look a bit closer.

Tomahawk missiles add size and cost to submarines.  The size increase is 20% or so, depending on the specific sub class and version.  The cost increase is harder to determine but one solid data point is the Virginia Payload Module (VPM) scheduled to be installed on the newest Virginias.  The cost increase is estimated to be around $500M which is a 20% increase over the base cost of around $2.5B.

By leaving out the VPM, we could build one extra Virginiaclass sub for every five subs built.  Are the added Tomahawks worth losing one extra sub for every five built?  To answer that, we need to recall the submarine’s mission(s).

The problem with “missions” is that people tend to assemble a laundry list and then, in discussions, assign by implication equal value to every mission.  For instance, here’s a partial list of submarine missions in no particular order.

• Anti-submarine warfare
• Anti-surface warfare
• Long range strike warfare
• Intelligence gathering
• Special operations forces support
• Presence
• Cross training with foreign navies
• Mine laying
• Carrier group escort
• Area denial
• Blockade

As we examine the list of missions, we see that long range strike warfare is on the list.  Ergo, we must have Tomahawks on every submarine!  See what I’ve done, there?  I’ve equated every mission.  They are all equally important.  Therefore, they must all be incorporated into the design of any sub.  This is what we do today but it is wrong.

What we should be doing is prioritizing the list of missions.  We should be asking ourselves, what is the most important mission?  We might also ask ourselves what the most likely mission is – it’s often not the same as the most important!  If we do that then we can begin to intelligently design a submarine and make informed tradeoffs between cost and capability.

In war, a submarine’s most important mission is anti-submarine warfare according to US Navy doctrine since the Cold War – I’m talking about attack subs, SSN’s, not ballistic missile submarines.  The main job of our submarines is to eliminate the enemy’s submarines.  A close second mission, but still second, is anti-surface warfare.  Every mission after that is extraneous, in a sense.  If, by eliminating all the other missions – Tomahawk capability, in this case – we could build an extra submarine for every five we now build, would this be worth the loss of 12-40 Tomahawks (we’re talking about Virginia class subs, now)?  I suggest it would be and would be well worth it. 

Consider, of the 50 or so attack subs we’d like to have, we could have 10 extra subs if we dropped the Tomahawk capability!  60 subs vs. 50.  That’s a trade I’ll take!

But wait!  What about the loss of Tomahawk strike capability?  Well, that’s a significant loss, no doubt.  However, we have plenty of alternate Tomahawk strike capability in the form of Burkes and we could have much more if we took the retiring Ohio class subs and converted them into additional SSGNs with 154 Tomahawks each.  The subs are already built so it would just require the incremental cost to modify them to launch cruise missiles.  Wiki reports the conversion cost at around $700M per sub in mid-2000’s dollars.  Relative to ship building costs, that’s quite reasonable.

Submarine Launched Tomahawk - Is It Needed?

You’re asking yourself, how does an SSGN square with my previous mission list and stated priorities of ASW and ASuW?  Well, an SSGN has a different mission priority – pure cruise missile strike warfare – so the SSGN falls in line with the concept of recognizing what the priority mission is.

We see, then, that we could have more subs for the same cost and maintain or increase our fleet wide Tomahawk strike capability if we choose to spend a little bit more. 

Note, the cost of one LCS would just about cover the cost of converting one SSBN to SSGN.  Would you rather have one LCS or one Ohio SSGN with 154 Tomahawk missiles?

So, does every submarine need to have Tomahawk launch capability?  My answer is no.  The Navy needs to look at submarine CONOPS and rethink submarine design and numbers.  We need to abandon the every-ship-must-be-capable-of-every-mission thinking that now dominates our design philosophy.

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