While in Norway recently, I was asked a question about how much it would cost to give Norway’s five existing Aegis-equipped frigates ballistic missile defense capabilities. This was raised as one hypothetical way the Norway might be able to contribute to the larger NATO missile defense program (and not as something that was expected to happen). At the time, I just said I didn’t know but guessed that it would be hundreds of millions of dollars. After returning, I came across a recent report about the cost of Spain similarly upgrading its Aegis ships. The numbers in this story suggest that the costs would be at least $300-$400 million.
The Norwegian Frigate Fridtjof Nansen (photograph source: Norway Ministry of Defense)
The head of the Spanish Naval Staff Planning Commission recently stated that, due to the cost involved, Spain would not upgrade their five Aegis-equipped ships for ballistic missile defense, at least not in the “short term,” although doing so remained a longer-term goal.  Vice Admiral Jose Antonio Ruesta Botella said that upgrading the frigates to be able to intercept ballistic missiles would involve three phases, costing 30 million euros for the initial “detection and tracking” phase, 80-90 million euros for the “integration and information” phase, and 120-130 million euros for the “confrontation” phase, for a total of about 250 million euros.
Current U.S. Navy Aegis BMD ships have either the 3.6.1 version of the Aegis BMD system or the more recent and capable Aegis 4.0.1 version. Future upgrades to the even more capable 5.0 and 5.1 versions are expected over the next decade, and new construction Aegis destroyers, scheduled to begin entering service in 2016, will have at least the 5.0 capability built in. According to the Missile Defense Agency, an in-service U.S. Navy Aegis ship with no ballistic missile upgrades can be upgraded to most current 4.0.1 Aegis BMD system for about $53 million, and a ship with only the earlier 3.6.1 version can be upgraded to the 4.0.1 version for about $45 to $55 million.
Assuming the cited 250 million euro ≈ $ 325 million cost was for all five Spanish ships, the cost would be about $65 million per ship, somewhat greater than the estimated $53 million cost for a U.S. ship. The Spanish newspaper indicates that the total $325 million cost may also include some missiles. However, the excess of roughly $60 million would not go very far in buying missiles costing more than $10 million each.
The five Norwegian Fridtjof Nansen class frigates are equipped with the SPY-1F version of the Aegis radar. This is a smaller (eight foot antenna diameter instead of the standard 12 foot antenna diameter on U.S. and other foreign ships) and less powerful version of the Aegis SPY-1 radar. This radar reportedly “has not been designed to provide ballistic missile defense capability through software and hardware modifications.” These ships have only 8 Mk 41 vertical launch system (VLS) launch cells (as compared to the 96 VLS cells on U.S. Aegis destroyers). Moreover, the Norwegian ships do not carry SM-2 air defense interceptors, but instead are armed for air-defense with Evolved Sea Sparrow Missiles, four of which can be carried in each VLS launch cell.
Even if the SPY-1F equipped Aegis system was not designed with ballistic missile defense upgrades in mind, it seems likely that it could be upgraded to have such a capability. However, this might cost significantly more than with one of the other SPY-1 radar versions. Thus the roughly $325 million cost estimate for upgrading the five Spanish frigates is likely a lower limit for the cost of similarly upgrading the five Norwegian frigates. If we add in roughly $100 million for 8-10 missiles, the total costs would likely come to at least $425 million.
Finally because of the significantly smaller size of their radars, the Norwegian ships would likely be even more reliant on outside sensor support than other types of Aegis ships. Making full use of the “launch-on-remote” or “engage-on-remote” strategies enabled by such outside data would require upgrading to at least the planned Aegis BMD version 5.1, which would likely involve greater costs.
 “Budget Constraints Prevent Spanish Navy Ships from Participating in NATO Shield,” BBC Worldwide Monitoring, November 27, 2012 (Original text in Spanish by Esteban Villarejo, “Anti-missile Shield: Spanish Frigate Participation Would Cost 250 Million Euros,” Spanish newspaper ABC website, November 24, 2012)
 Ronald O’Rourke, “Navy Aegis Ballistic Missile Defense (BMD) Program: Background and Issues for Congress,” Congressional Research Service, RL33745, July 2, 2012, p. 7.
 According to MDA, SM-3 Block-IBs are expected to cost about $12-$15 million each, and Block IIAs to cost about $20-$24 million each. (O’Rourke,” Navy Aegis Ballistic Missile Defense,” p. 4). SM-3 Block IA missiles cost about $10 million each.
 Norway’s New Nansen Class Frigates: Capabilities and Controversies,” Defense Industry Daily, June 7, 2006.