U.S. Navy: Conventional Trident on Hold

Congress has denied major funding in the Fiscal Year 2007 budget for the Navy to develop and deploy non-nuclear Trident missiles in the fleet's ballistic-missile submarines (SSBNs). The program, small but increasingly controversial, is for each of the 14 Trident submarines of the Ohio (SSBN-726) class to carry two such missiles with non-nuclear warheads when on deterrent patrol. The other 22 Trident D-5 missiles in each boat would retain the current payload of multiple-reentry vehicles with W76 or W88 thermonuclear warheads.

The conventional Trident modification (CTM) program was specifically endorsed by the recent Quadrennial Defense Review (QDR), which directed the deployment of non-nuclear Trident missiles within two years, i.e., by 2008.1 The Defense Department had requested $127 million for FY 2007, a very small amount when considering defense hardware programs. Some $30 million in research funds were approved. Many in Congress appear to support the idea of a conventional weapon for the mission-which the Pentagon calls "prompt global strike"-but are not in a hurry to put the modified Trident missiles to sea.

The CTM missiles-designed to destroy point targets-are intended to give the SSBNs a greater role in combating terrorism. The U.S. submarine force already claims "Our contributions to the Global War on Terror are significant, and our ability to meet potential future threats is unsurpassed."² However, the submarine community has provided few details to the public-or even to Congress-about such activities. The modified Trident missiles will provide a strike capability with a range and speed-of-flight not now possible with the Navy's principal strike weapons-carrier-based F/A-18 Hornets and ship- and submarine-launched Tomahawk cruise missiles.

The CTM missile concept has already been demonstrated. More than a decade ago-on 19 November 1993-the USS Nebraska (SSBN-739) test launched a Trident D-5 missile carrying at least two non-nuclear warheads: One of the warheads carried steel rods and the other a concrete "slump" intended to smash into bunkers buried deep underground. The Nebraska launches were the first of a series of Trident tests using conventional warheads. Subsequent Trident test launches related to the CTM concept have been flown with simulated nuclear and non-nuclear warheads.

Two Trident tests-one on 22 October 2002, and one on 1 March 2005-evaluated a three-axis flap system developed by Lockheed Martin that enables the re-entry vehicles to be steered with an accuracy of some 30 feet using Global Positioning System (GPS) guidance. The 2005 test firing, from the submarine Tennessee (SSBN-734), was launched to a range of only 1,200 nautical miles. Maximum range for these weapons will be 6,000 nautical miles. The kinetic force of the warheads will enable them to penetrate protected structures. A total of 24 missiles are scheduled to be fitted with those warheads, sufficient to provide each at-sea SSBN with two CTM missiles.

But there are strongly differing views about the CTM program. "It's a stupid idea, but its time has come," said one Navy officer to this columnist. Another, Captain Timothy Lindstrom, chief of staff of Submarine Group 10, said that it's "a natural progression of the efforts we've made in the last few years toward enhancing the flexibility and adaptability of these ships to account for the end of the Cold War and the onset of the Global War on Terror."³

The differing views of the CTM missile program emerge from the weapon's obvious advantages and disadvantages. The advantages are providing a rapid, long-range strike capability, the kinetic energy of an SLBM warhead, which could be especially useful for attacking protected or underground facilities, and taking advantage of the large number of submarine missiles-336 SLBMs in the 14 existing SSBNs. The probability of the United States launching a nuclear strike in the foreseeable future is considered very small. Indeed, the extra-national character of terrorist movements makes targeting nuclear weapons against them probably impossible.

Four of the original 18 Trident submarines are being converted to multipurpose SSGN configurations and many observers believe that the number of SSBNs will be further reduced in the next few years. A recent Naval Research Advisory Committee study of future threats-related science and technology requirements states:

In the context of traditional strategic deterrence of nuclear attacks, the Panel envisions a reduction in emphasis. This will likely be manifested in a reduction in the number of Trident strategic missile submarines (SSBN) from the current force of 14 submarines, although the Navy's 30-year shipbuilding plan as presented to Congress shows a force of [14] SSBNs for the entire term.⁴

Thus, the Trident modification program could enhance the value of the SSBN force in a future having a reduced requirement for nuclear strike.

The disadvantages of the CTM program include:

* Strategic warning: An SLBM launch can be detected by warning systems of several countries. Even with the proverbial telephone call-which may or may not reach the proper people in time-a government detecting an SLBM launch could react impulsively. For example, a previously announced launch of a Norwegian research rocket on 25 January 1995, was evaluated as a hostile missile launch by the Russian strategic defense forces and set off alarms; the Russian warning system alerted President Boris Yeltsin and, reportedly, nuclear retaliatory options were considered "just in case."

Launch detection systems, however, are finite and usually focused on specific land launch sites. For advanced systems, a calculation of expected trajectory can be quick, accurate, and constantly updated; for more primitive systems they will be far less so. Regardless, should the target be inland, the trajectory may have political implications as the missile passes over friendly or neutral countries.

* Third-stage booster: Following a Trident SLBM launch, the missile's third-stage booster, weighing several thousand pounds, will fall to earth. This concern could greatly inhibit conventional SLBM launch locations with trajectories over friendly or neutral territory. Although the booster impact footprint can be largely predicted and controlled, the concern for potential political as well as physical ramifications are considerable.

* Submarine detectability: Submarine survivability is a key factor in SSBN operations. The launch of one or two conventional missiles could compromise the location of a Trident submarine if a hostile nation has the ability (through satellites, land-based radar, seafloor acoustic systems) to detect such launches. Given a submarine's mobility, this is considered a secondary issue today. However, the implications of such a future compromise of SSBN location are far from clear.

Also, unlike strategic nuclear attacks, the rapid use of CTM missiles may require two-way communications. This, too, could be a factor in an enemy determining the location of an SSBN.

* Submarine availability: Perhaps onehalf of the Navy's 14 Trident submarines are at sea at any given time-about seven submarines world-wide. While their patrol areas are classified, a significant fraction is undoubtedly deployed in the North Atlantic and North Pacific because of the potential nuclear threats from Russia, North Korea, and China. Accordingly, the number of SSBNs available to cover such terrorist-threat areas as the Middle East and North Africa with conventional Tridents could be limited. And, of course, the total platform pool for the CTM program is 14 submarines-and probably fewer in coming years.

A complement or alternative to the modified Trident missiles could be a supersonic cruise missile. The subsonic Tomahawk is considered too slow for quick-response strikes against specific targets. Several programs are underway that could provide a supersonic land-attack missile with a Tomahawk's range (1,000 nautical miles), payloads, and accuracy. This missile could be highly effective against urban as well as rural targets.

A major advantage of Tomahawk-type missiles is the large number of launch platforms available-all U.S. attack submarines, cruisers, and destroyers can carry Tomahawks as well as the four ex-Trident SSGNs (which can each carry up to 154 Tomahawk-type missiles). More than 125 launch platforms could thus be available for a future high-speed Tomahawk, including perhaps 45 nuclear submarines, compared to a force of 14 or fewer Trident SSBNs.

Perhaps the major advantage of the modified Trident is the slump and rod warheads-with kinetic energy-could be highly effective against buried installations. But penetrating warheads for other weapons have long been in development. The conventional Trident modification holds much promise for the future fleet, but with the hiatus recently provided by congressional action, alternative options must be objectively considered.