Japan may build ships solely for missile defence

Japan tells U.S. of plan to build ships solely for missile defense

When I read this article, it seemed to be a very poor decision to me.

Yes, if you cannot put the missile defence system on land, putting it at sea is a viable alternative. And yes, building a ship purely for missile defence will be cheaper than building a multi-mission Aegis destroyer, IF you look purely at the shipbuilding cost itself.

But ships are not a one-off expenditure. They have a life cycle of 20 to 30 years, during which they need to go for regular maintenance. More importantly, they need to be manned. Training people to man these ships, and rotating the crew, is not going to be that much different from manning regular ships. Which means personnel-related expenditure (pay and training) will likely be similar to those for other ships as people will be rotated between these specialised ships and the other ships in the JMSDF.

So on paper, it looks like a good idea. But when you look beyond the ship itself and think about the entire system required to sustain these specialised ships, the actual costs involved may not be much more different than getting regular warships equipped for a wider range of missions.

Let's think about things as a system instead of specific hardware.