Navy Trident Submarine Conversion (SSGN) Program: Background and Issues for Congress
Navy Trident Submarine Conversion (SSGN)
Program: Background and Issues for
Specialist in Naval Affairs
Foreign Affairs, Defense, and Trade Division
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). Initial Operational Capability
(IOC) for the program was declared on November 1, 2007. The total estimated cost of
the program is about $4.0 billion. This report will be updated as events warrant.
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).th
The first Trident entered service in 1981, the 18 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 were later 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 were converted to carry the
same D5 missiles carried by the 9th through 18th Tridents. These Trident D5 conversions are not
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
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.
The Bush 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 Bush administration, prior to submitting this budget, had
highlighted the Trident SSGN concept as an example of defense transformation, it came
as somewhat of a surprise, particularly to supporters of the SSGN concept, that the Bush
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
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
further discussion, see CRS Report RL30033, Arms Control and Nonproliferation Activities: A
Catalog of Recent Events, coordinated by Amy F. Woolf (out of print; available from the author).
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
January 1997, pp. 7-9.
committing to the refueling and conversion of SSBNs 726 and 728 on a timely basis5 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
Bush Administration subsequently pursued the program as a four-boat effort.
Description of the Conversion. The Tridents as converted can carry up to 154
Tomahawk cruise missiles (or other non-strategic land attack missiles ) and 66 Navy6
SEAL special operations forces (SOF) personnel. Each boat retains its 24 large-diameter
SLBM launch tubes but the boats have been modified as follows:
!SLBM tubes 1 and 2 were 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).7 Other
spaces were converted to berth and support 66 SOF personnel.
!Tubes 3 through 24 were modified to carry 7 Tomahawks each, for a total
of 154 Tomahawks. Alternatively, tubes 3 through 10 can be used to
carry additional SOF equipment and supplies; leaving tubes 11 through
!The Trident SLBM fire control systems were replaced with tactical
missile fire control systems, and certain other systems aboard the boats
In addition to these changes, each boat underwent 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 more than a year, during which time it is to be operated by dual (Blue and Gold) crews
rotating on and off the ship every three or four months. The aim is to have two of the four
SSGNs continuously forward deployed until the ships are decommissioned in the late
2020s. As of September 30, 2007, SSBNs 726 and 727 were homeported in Puget Sound
at Bangor, WA, while SSBNs 728 and 729 were homeported at Kings Bay, GA. The
report of the 2001 Quadrennial Defense Review, submitted to Congress in September
5 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.
6 The Navy’s SOF personnel are called SEALs, which stands for Sea, Air, and Land.
7 The ASDS is a new mini-submarine for Navy SEALs; the DDS is a less-capable predecessor.
the Western Pacific.8 SSBNs 726 and 727, though homeported at Bangor, are operated out
of the U.S. territory of Guam in the Western Pacific.9
The SSGNs are to operate as covert platforms for conducting strike (i.e., land attack)
and SOF-support missions. In the covert 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 viewed as 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.
Trident SSGNs and Navy Transformation. The Bush Administration and
other supporters of the Trident SSGN program highlighted the 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. Others observers demurred, arguing that Navy has converted older SSBNs into
SOF-support submarines in the past, that the larger number of cruise missiles that the
SSGNs carry is 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 for research and
development efforts supporting 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 new ideas,
such as using submarines to deploy large-diameter, highly capable unmanned underwater
vehicles (UUVs). Even if one judges the program not transformational, one might still
judge it 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 estimates for a four-boat program of about
$2.4 billion in 1999-2000, and $3.3 billion to $3.5 billion in 2001-2002. 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 equates to $1,777.9 million in constant
FY2005 dollars, or an average of about $44.4 million per boat per year in constant
8 U.S. Department of Defense, Quadrennial Defense Review Report, September 30, 2001, p. 27.
9 Sources: Oyaol Ngirairikl, “USS Ohio Moors at Bravo Wharf,” Navy News Service, January 17,
2008, and Associated Press, “Submarine Ohio Underway in Pacific,” NavyTimes.com, October
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
(millions of then-year dollars, rounded to nearest million)
00 01 02 03 04 05 06 07 08 09 10 11 12 13 Total
R&D 13 36 72 82 65 19 23 25 0 0 0 0 0 0 336
SCN 0 0 354 999 1175 515 283 0 0 0 0 0 0 0 3326
OP N 0 0 0 110 0 120 6 10 134 3 1 0 0 0 384
Total 13 36 426 1191 1241 654 312 35 134 3 1 0 0 0 4046
Source: Navy Office of Legislative Affairs, March 18, 2008. Totals may not add due to rounding. R&D
is funding in the Navy’s Research, Development, Test & Evaluation (RDT&E) appropriation account in
program element (PE) 0603563N (FY2000) and PE 0603559N (FY2001-FY2007). SCN is procurement
funding in the Navy’s Shipbuilding and Conversion, Navy (SCN) account in Line Item (LI) 2017. OPN is
procurement funding in the Navy’s Other Procurement, Navy (OPN) account in LIs 0950 and 1010.
Program Schedule. All four Trident conversions have been completed, and
Initial Operational Capability (IOC) for the program was declared on November 1, 2007.
SSBN-726, the first ship to be converted, reportedly began its first operational10
deployment as an SSGN in October 2007.
Shipyards and Prime Contractor. The refuelings and conversions were
performed by the Puget Sound Naval Shipyard (PSNSY) at Bremerton, WA SSBNs 726
and 727) and the Norfolk Naval Shipyard (NNSY) at Norfolk, VA (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
U.S. perspective at least, a potential issue regarding the counting of “phantom” strategic11
nuclear warheads on converted Trident SSGNs.
10 Associated Press, “Submarine Ohio Underway in Pacific,” NavyTimes.com, October 23, 2007.
The conversion of SSBN-726 began in November 2002 and was completed in December 2005;
the ship reentered service in February 2006. The conversion of SSBN-728 began in August 2003
and was completed in April 2006; the ship reentered service in May 2006. The conversion of
SSBN-727 began in March 2004 and was completed in November 2006; the ship reentered
service in June 2007. The conversion of SSBN-729 began in March 2005 and was completed in
December 2007; the ship reentered service in March 2008.
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
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 boats? 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 How would a continuing shortage of Advanced SEAL
Delivery Systems (ASDSs) affect the operational utility of the SSGNs?
Legislative Activity for FY2009
The FY2009 defense appropriations act (Division C of H.R. 2638/P.L. 110-329 of
September 30, 2008) approved the Navy’s FY2009 request for $3 million in Other
Procurement, Navy (OPN) funding for the SSGN program.
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, resolved
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