Order Code RS21007
Updated May 17, 2007
Navy Trident Submarine Conversion (SSGN)
Program: Background and Issues for
Congress
Ronald O’Rourke
Specialist in National Defense
Foreign Affairs, Defense, and Trade Division
Summary
The FY2006 budget completed the funding required in the Shipbuilding and
Conversion, Navy (SCN) account for the Navy’s program to refuel and convert four
Trident ballistic missile submarines (SSBNs) into cruise-missile-carrying and special
operations forces (SOF) support submarines (SSGNs). The first two converted SSGNs
reentered service in 2006; the other two are scheduled to reenter service in 2007. The
total estimated cost of the four-boat conversion program is about $4.0 billion. This
report will be updated as events warrant.
Background
Trident Submarines. The Navy procured 18 Ohio (SSBN-726) class nuclear-
powered ballistic missile submarines (SSBNs) between FY1974 and FY1991 to serve as
part of the U.S. strategic nuclear deterrent force. They are commonly called Trident
submarines because they carry Trident submarine-launched ballistic missiles (SLBMs).
The first Trident entered service in 1981, the 18th in 1997. The first 8 (SSBNs 726
through 733) were originally armed with Trident I (C4) SLBMs; the final 10 (SSBNs 734
through 743) were armed with larger and more powerful Trident II (D5) SLBMs. The
boats were originally designed for a 30-year life but have now been certified for a 42-year
life, composed of 20 years of operation, a two-year mid-life nuclear refueling overhaul,
and then another 20 years of operation.
Origin of SSGN Conversion Concept. The Clinton Administration’s 1994
Nuclear Posture Review (NPR) recommended a strategic nuclear force for the START II
strategic nuclear arms reduction treaty that included 14 Tridents (all armed with D5
missiles) rather than 18.1 This recommendation prompted interest in Congress and
1 Consistent with this recommendation, the 5th through 8th Tridents (SSBNs 730 through 733) are
(continued...)

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elsewhere in the idea of converting the first 4 Trident SSBNs (SSBNs 726 through 729)
into non-strategic submarines called SSGNs,2 so as to make good use of the 20 years of
potential operational life remaining in these four boats and bolster the U.S. attack
submarine (SSN) fleet, which has been significantly reduced in recent years. The Bush
Administration’s 2002 NPR retained the idea of reducing the Trident SSBN force to 14
boats.
Some observers supported the SSGN conversion concept3 while a few others
questioned it.4 The Navy in the late 1990s generally supported the concept in principle
but also expressed concern over its ability to finance all four conversions while also
funding other priorities. Congress, as part of its action on the proposed FY1999 defense
budget, directed the Secretary of Defense to report on the issue to the congressional
defense committees by March 1, 1999. The report was delivered to Congress in classified
and unclassified form in June 1999. The Bush Administration highlighted the program
as an example of defense transformation.5
The Administration, in its amended FY2002 defense budget submitted to Congress
in June 2001, requested funding to begin the refueling and conversion of SSBNs 727 and
729, and additional funding to begin the inactivation and dismantlement of SSBNs 726
and 728. Since the Administration, prior to submitting this budget, had highlighted the
Trident SSGN concept as an example of defense transformation, it came as somewhat of
1 (...continued)
being converted to carry the same D5 missiles carried by the final 10 Tridents. These Trident D5
conversions are not to be confused with the separate Trident SSGN conversions discussed in this
report. The recommendation for a 14-boat force was made in expectation that the START II
treaty would enter into force. The treaty has not entered into force. Section 1302 of the FY1998
defense authorization act prohibited U.S. strategic nuclear forces from being reduced during
FY1998 below START I levels (including 18 Trident SSBNs) until the START II treaty entered
into force. This prohibition was extended through FY1999 by Section 1501 of the FY1999
defense authorization act and was made permanent by Section 1501 of the FY2000 defense
authorization act. The latter provision, however, also contained a section that would permit a
reduction to 14 Trident SSBNs, even without START II entering into force, if the President
certifies to Congress that this reduction would not undermine the effectiveness of U.S. strategic
nuclear forces. For a general discussion of the START Treaties, see CRS Report RL30033, Arms
Control and Nonproliferation Activities: A Catalog of Recent Events, coordinated by Amy F.
Woolf.
2 The G in SSGN stands for guided missile, a reference to the Tomahawk cruise missile or a
potential future non-strategic land-attack missile.
3 See, for example, William P. Houley, “Making the Case for SSGNs,” U.S. Naval Institute
Proceedings, July 1999, pp. 47-49; Ernest Blazar, “A ‘New Dimension’ in Warfighting
Capabilities,” Sea Power, July 1999, pp. 37-40; Andrew Krepinevich, “The Trident ‘Stealth
Battleship,’ An Opportunity for Innovation, CSBA Backgrounder, February 24, 1999; Owen R.
Jr. Cote, “How To Spend Defense Dollars,” Washington Times, January 15, 1999, p. 19.
4 See Norman Polmar, “A Submarine for All Seasons?” U.S. Naval Institute Proceedings, August
1999, pp. 87-88, and Norman Polmar, “The Submarine Arsenal Ship,” The Submarine Review,
January 1997, pp. 7-9.
5 For more on defense transformation, see CRS Report RL32238, Defense Transformation:
Background and Oversight Issues for Congress, by Ronald O’Rourke.

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a surprise, particularly to supporters of the SSGN concept, that the Administration
requested funding to convert only two of the four Tridents. Navy officials said the
decision was driven in part by Navy budget constraints, and that the deadline for
committing to the refueling and conversion of SSBNs 726 and 728 on a timely basis6 had
passed some time between late 2000 and June 2001. This also came as a surprise to some
observers, since the Navy during the intervening months had not done much to publicize
the impending deadline. The Navy later explained, however, that refueling and
converting SSBNs 726 and 728 would still be possible if funds were provided in FY2002,
though the schedule for planning and carrying out the operation would now be less than
optimal. Congress, in marking up the FY2002 budget, increased funding for the program
to the level the Navy said was needed to support a four-boat conversion program. The
Administration subsequently pursued the program as a four-boat effort.
Description of the Conversion. The Tridents as converted are to carry up to
154 Tomahawk cruise missiles (or other non-strategic land attack missiles ) and 66 Navy
SEAL special operations forces (SOF) personnel.7 Each boat is to retain its 24 large-
diameter SLBM launch tubes but be modified as follows:
! SLBM tubes 1 and 2 are altered to serve as lockout chambers for the SOF
personnel. Each chamber is equipped to connect to an Advanced SEAL
Delivery System (ASDS) or Dry Deck Shelter (DDS).8 Other spaces
aboard the submarine are converted to berth and support 66 SOF
personnel.
! Tubes 3 through 24 are modified to carry 7 Tomahawks each, for a total
of 154 Tomahawks. Alternatively, tubes 3 through 10 could be used to
carry additional SOF equipment and supplies; leaving tubes 11 through
24 to carry 98 missiles.
! The Trident SLBM fire control systems are replaced with tactical missile
fire control systems, and certain other systems aboard the boats are
modernized.
In addition to these changes, each boat undergoes a mid-life engineering (nuclear)
refueling overhaul (ERO). Without EROs, the boats would have exhausted their nuclear
fuel cores and been inactivated in the FY2003-FY2005 time frame.
Missions and Concept of Operations. Each SSGN is to deploy for a period
of 15 months, during which time it is to be operated by multiple crews rotating on and off
the ship. The aim is to have two of the four SSGNs continuously forward deployed until
the ships are decommissioned in the late 2020s. The boats are to operate as covert
platforms for conducting strike (i.e., land attack) and SOF-support missions. In the covert
6 As a matter of policy for ensuring the safety and reliability of nuclear propulsion, nuclear-
powered ships with exhausted nuclear fuel cores are not permitted to wait any significant time
between the exhaustion of their nuclear fuel cores and the completion of preparations to refuel
them. If a ship cannot go immediately into a refueling operation, it is instead permanently
inactivated. A decision to refuel a ship must therefore be made by a certain date prior to the
refueling, so that the fuel cores and other equipment needed can be ordered and manufactured
in time to be ready for installation when the ship comes into dry dock.
7 The Navy’s SOF personnel are called SEALs, which stands for Sea, Air, and Land.
8 The ASDS is a new mini-submarine for Navy SEALs; the DDS is a less-capable predecessor.

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strike role, the boats can fulfill a substantial portion of the in-theater Tomahawk missile
requirements that are established by regional U.S. military commanders, and thereby
permit forward-deployed multimission Navy surface combatants and SSNs to concentrate
on other missions. In their SOF-support role, the SSGNs can be functional replacements
for the James K. Polk (SSN-645) and the Kamehameha (SSBN-642) — two older-
generation SSBNs that were converted into SSNs specifically for supporting larger
numbers of SOF personnel. The Polk was retired in 1999 at age 33; the Kamehameha
was retired in 2002 at age 36. The report of the 2001 Quadrennial Defense Review,
submitted to Congress in September 2001, directed the Secretary of the Navy to explore
options for homeporting SSGNs in the Western Pacific.9 One candidate home port in this
area is the U.S. island territory of Guam, where the Navy has forward-homeported three
Los Angeles (SSN-688) class attack submarines. Another possible location is Pearl
Harbor, Hawaii.
Trident SSGNs and Navy Transformation. As mentioned earlier, the Bush
Administration highlighted the Trident SSGN program as an example of defense
transformation, citing the conversion of a strategic-nuclear-forces platform into a non-
strategic platform, the large number of cruise missiles that an SSGN will carry (which is
several times the number that can be carried by a standard Navy attack submarine), and
the large payload volume of the boats for carrying future advanced payloads. Some
supporters of the program outside the Administration agree with this view. Others demur,
arguing that Navy has converted older SSBNs into SOF-support submarines in the past,
that the larger number of cruise missiles that the SSGNs will carry can be viewed as more
of a quantitative difference than a qualitative one, and that funding the Trident SSGN
program may actually have slowed the transformation of the Navy’s submarine force by
reducing the amount of funding available to the submarine community for research and
development programs aimed at developing more radical and transformational changes
to the Virginia-class attack submarine design. The submarine community intends to
maximize the transformational value of the SSGNs by using them as at-sea test beds for
conducting experiments on transformational ideas, such as using submarines as platforms
for deploying large-diameter, highly capable unmanned underwater vehicles (UUVs).
Even if one judges the program not transformational, one might still judge it to be cost
effective in terms of the capabilities it provides and in realizing a full, 42-year return on
the original procurement cost of the boats.
Program Cost. As shown in Table 1, the Navy estimates the total cost for
refueling and converting four Tridents (including both research and development as well
as procurement costs) at about $4.0 billion, or about $1 billion per boat. This figure
represents a substantial increase over earlier cost estimates: The cost of a four-boat
conversion program was estimated at about $2.4 billion in 1999-2000, and $3.3 billion
to $3.5 billion in 2001-2002. The estimated cost of a four-boat program thus increased
more than 60% since 1999-2000. Refueling and converting four Tridents avoids a near-
term expenditure of about $440 million to inactivate and dismantle them. The estimated
net near-term additional cost to the budget to convert the 4 boats rather than inactivate and
dismantle them is thus $3.56 billion ($4.0 billion less $440 million), or about $890
million per boat. DOD estimated in 1999 that the operating and support (O&S) cost for
two SSGNs over 20 years would be $1,645.3 million in constant FY1998 dollars, which
9 U.S. Department of Defense, Quadrennial Defense Review Report, September 30, 2001, p. 27.

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equates to $1,777.9 million in constant FY2005 dollars, or an average of about $44.4
million per boat per year in constant FY2005 dollars. Using this figure, the total 20-year
life-cycle cost for four Trident SSGNs (including research and development costs, annual
operation and support costs, and eventual inactivation and dismantlement costs) would
be roughly $7.6 billion in constant FY2005 dollars.
Table 1. FY2000-FY2013 Funding for SSGN Conversion Program
(by fiscal year, in millions of then-year dollars, rounded to nearest the million; totals
may not add due to rounding)
00
01
02
03
04
05
06
07
08
09
10
11
12
11
Total
R&D
13
36
72
82
65
19
23
26
0
0
0
0
0
0
336
SCN
0
0
354
999
1175
515
283
0
0
0
0
0
0
0
3326
OPN
0
0
0
110
0
120
6
10
134
3
1
0
0
0
384
Total
13
36
426
1191
1240
654
312
36
134
3
1
0
0
0
4046
Source: Navy Office of Legislative Affairs, March 28, 2007. R&D is funding in the Navy’s Research,
Development, Test & Evaluation (RDT&E) appropriation account in program element (PE) 0603559N.
SCN is procurement funding in the Navy’s Shipbuilding and Conversion, Navy (SCN) account. OPN is
procurement funding in the Navy’s Other Procurement, Navy (OPN) account.
FY2008 Funding. As shown in Table 1, the Navy for FY2008 is requesting $134
million funding in the Other Procurement, Navy (OPN) account for the program.
Program Schedule. The first Trident conversion, for SSBN-726, began in
November 2002 and was completed in January 2006. The ship reentered service as an
SSGN on February 7, 2006, and is scheduled to make its first operational deployment as
an SSGN in late 2007. The second conversion, for SSBN-728, began in August 2003 and
was completed in April 2006. The ship reentered service as an SSGN on May 25, 2006.
The third, for SSBN-727, began in March 2004 and was to be completed in December
2006. The fourth, for SSBN-729, began in March 2005 and is to be completed in
September 2007.10
Shipyards and Prime Contractor. The Puget Sound Naval Shipyard (PSNSY)
at Bremerton, WA, was assigned to do the refuelings and conversions of SSBNs 726 and
727, while the Norfolk Naval Shipyard (NNSY) at Norfolk, VA, was assigned to do the
refuelings and conversions of SSBNs 728 and 729. General Dynamics’ Electric Boat
Division (GD/EB) of Groton, CT and Quonset Point, RI, the designer and builder of all
18 Tridents, is the prime contractor for the program. GD/EB is the conversion execution
integrator for all four boats and is managing the completion of conversion construction
activities.
Arms Control and “Phantom Warhead” Issue. On May 13, 2002, the
Administration announced that it had reached an agreement with Russia on a new
strategic nuclear arms treaty that would require each side to reduce down to 1,700 to
2,200 strategic nuclear warheads by 2012. The agreement appears to resolve, from the
10 For an article providing additional details on the schedules for the four ships as of February
2007, see Geoff Fein, “Ohio-Class Conversions Nearing IOC, Lead Ship To Deploy Late ‘07,”
Defense Daily, February 15, 2007.

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U.S. perspective at least, a potential issue regarding the counting of “phantom” strategic
nuclear warheads on converted Trident SSGNs.11
Potential Oversight Issues for Congress
Potential oversight questions for Congress include the following: Why did the
estimated cost of a four-boat conversion program increase by more than 60% since 1999-
2000? Is the Navy adequately funding programs for unmanned underwater vehicles
(UUVs) and other advanced payloads so as to take full advantage of the SSGNs’ large
payload capacity? If a decision is made to reduce the Trident SSBN force from 14 boats
to 12, what would be the potential costs and merits of expanding the SSGN conversion
program to include two additional Trident SSBNs? Since the Navy’s plan for maintaining
a fleet in coming years of 313 ships includes 4 SSGNs, why does the Navy’s 30-year
shipbuilding include no replacements for the 4 SSGNs, resulting in the disappearance of
SSGNs from the fleet by 2028?12
Legislative Activity For FY2008
FY2008 Defense Authorization Bill (H.R. 1585). The House Armed Services
Committee, in its report (H.Rept. 110-146 of May 11, 2007) on the FY2008 defense
authorization bill (H.R. 1585), recommended approval of the Navy’s FY2008 request for
Other Procurement, Navy funding for the SSGN program.
11 Under the previous START strategic nuclear arms reduction treaties, the SSGNs would remain
accountable as strategic nuclear launch systems because they would retain their large-diameter
SLBM launch tubes. Four SSGNs, even though they carried no SLBMs, would be counted as
carrying 96 Trident SLBMs each with 4 nuclear warheads, for a total of 384 warheads. Having
to include 384 “phantom” warheads within the allowed START II U.S. strategic nuclear force
of 3,500 warheads was viewed as problematic from a U.S. perspective, since it would deprive the
United States of about 11% of its permitted warheads. The alternative of asking Russia to
exempt SSGNs from the counting scheme was also viewed as problematic, since Russia would
likely either refuse or ask for something significant in return. The phantom warhead issue would
have been even more pronounced under a potential START III treaty that might have limited the
United States to 2,500 or fewer nuclear warheads. The phantom warhead issue appeared to have
receded for a time due to the Administration’s originally stated intention to not complete
ratification of START II, and to instead reduce U.S. strategic nuclear forces unilaterally, without
the use of new treaties. This would leave only the older START I treaty, with its much higher
permitted nuclear force levels, as an in-force treaty against which the SSGNs could be counted.
On February 5, 2002, however, Secretary of State Colin Powell announced that the United States
was seeking a legally binding agreement with Russia on future levels of strategic nuclear
weapons. This created a potential for the phantom warhead issue to once again become
potentially relevant. The new U.S.-Russian arms treaty announced on May 13, 2002, resolves
the issue from the U.S. perspective by counting only operationally deployed strategic nuclear
warheads and not strategic nuclear launch systems. Since the SSGNs will not deploy strategic
nuclear warheads, the Administration is excluding them from the treaty’s limit of 1,700 to 2,200
operationally deployed warheads. Russia to date has not publicly objected to this interpretation.
12 For more on the 313-ship fleet and the 30-year shipbuilding plan, see CRS Report RL32665,
Navy Force Structure and Shipbuilding Plans: Background and Issues for Congress, by Ronald
O’Rourke.
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