Moving U.S. Forces: Options for Strategic Mobility Section 11 of 12
February 1997

Appendix C

Key Assumptions About
Mobility Operations

In recent analyses such as the Mobility Requirements Study Bottom-Up Review Update (MRS BURU), Defense Department mobility planners have used a series of technical assumptions that, on balance, some analysts have characterized as optimistic. This appendix reviews the assumptions that have the greatest effect on mobility requirements.



Warning Time and the Decision to Begin Deployments

One lesson from the Persian Gulf War was that unambiguous warning and quick decisionmaking are the keys to deploying forces rapidly. Assumptions about warning time are critical because if the United States had less advance notice of a conflict, it would need more airlift and prepositioning to get forces to the theater and halt an enemy's attack. With more warning, the Department of Defense (DoD) might be able to rely more extensively on sealift.(1) If intelligence is clear that an attack is imminent and decisionmakers act quickly on that information, DoD can begin to smooth the way for further deployments.

The MRS BURU assumes that in a future conflict, critical decisions will be made in a timely fashion. Unfortunately, neither unambiguous warning nor quick decisions were apparent in July and August 1990, when Iraq was threatening Kuwait, which has led some military officials to call the MRS BURU's assumptions about warning time unrealistic. However, press reports suggest that the MRS BURU assumed less warning time than DoD used in its 1992 Mobility Requirements Study.(2)

Should DoD expect very little warning? In the case of the Bottom-Up Review's planning scenarios--major regional conflicts in the Persian Gulf and Korea--the answer may well be yes. Some defense officials believe that the Iraqi military has improved its ability to move smaller numbers of divisions with less notice than in the past.(3) And with much of the large North Korean army stationed close to the demilitarized zone, it would seem prudent to make such an assumption for a potential conflict on the Korean Peninsula.

For its part, DoD has prepared itself to respond more rapidly today. Military officials quickly activated land-based and afloat prepositioning forces near the Persian Gulf in several recent incidents in which Iraqi forces appeared to be on the move.(4) After one such operation, the October 1994 deployment known as Vigilant Warrior, the United Nations designated the 32nd parallel as a "no-drive zone," strengthening the existing "no-fly zone." Thus, the international community would consider any movement by Iraqi forces south of that line as a sign of probable attack.(5) After Saddam Hussein involved Iraqi troops in a September 1996 conflict among Kurdish factions, the United States expanded the no-fly zone to include the 33rd parallel.

Even when warning is clear, however, decision-makers do not always act quickly on that intelligence. For example, satellite data before August 2, 1990, showed that Iraqi troops were massing on the Kuwaiti border. But many U.S. intelligence analysts believed that Iraq was merely trying to intimidate its neighbor into lowering oil production.(6) Moreover, commanders did not take immediate steps to begin a deployment, presumably because U.S. officials were still broaching the idea of allowing military forces to operate in the Gulf with the leaders of those countries. In most other cases in the 20th century, attacks were foreshadowed by prolonged tension, yet leaders were surprised not because of a lack of intelligence but because of their political disbelief.(7)



The Availability of Personnel

Another factor that could affect the pace of deliveries to a future conflict is the early availability of personnel to crew planes and ships, maintain equipment, and help establish DoD's transportation network. Reservists are particularly important for airlift operations: during the Persian Gulf War, they made up 60 percent of C-5 aircrews, about 50 percent of C-141 aircrews, and significant numbers of personnel in maintenance and aerial port squadrons. For sealift, the Navy does not have a cadre of reservists to fill out crews but rather relies predominantly on U.S. merchant mariners to man the Ready Reserve Force. However, reservists do fill many of the Army's transportation units that would help set up port operations and load and unload ships.

In the past, DoD has relied heavily on volunteers from the reserves before the President calls them up. Although useful, the skills of volunteers do not necessarily match those needed during the start of a conflict. Thus, to use mobility forces to their fullest potential, reservists must be called up quickly. Similarly, tapping merchant mariners as soon as possible is critical to getting sealift ships under way.

Recent history does not clearly show whether reservists could be activated quickly enough to help complete deliveries over the first two to three weeks of a conflict. At the time of the Gulf War, for example, the President did not authorize activation of the first reserve aircrews (two C-5 and three C-141 units) until August 23, 1990--16 days after the start of deployments.(8) In 1994, by contrast, the President authorized a limited call-up of reserve personnel for U.S. operations in Haiti within 24 hours of DoD officials' requesting such authority.

During Desert Shield, shortages of certain types of skilled personnel kept DoD from filling some of its sealift crews within required times.(9) Despite a recent exercise by the Maritime Administration, which showed that sufficient manpower is available for the Ready Reserve Force, the declining number of U.S. merchant mariners has raised concern that DoD might experience crew shortages in the future, thus delaying deployments. The Navy's plan to retire 21 ships from the Ready Reserve Force by 2002 may eliminate such shortages. Moreover, ships that are kept in higher readiness categories (four- or five-day reduced operating status) would have higher priority for crewing. Those are also the ships that would transport the initial surge of combat equipment to reinforce the units DoD plans to use to halt an enemy attack. Thus, although the Navy might possibly experience some delays associated with having too few merchant mariners, units that would be among the first to sail on DoD's sealift ships would probably not be as affected as units that would deploy later. However, too slow a call-up of reservists in port-control and transportation units could hinder the loading and unloading of ships.



Early Access to Commercial Planes and Ships

During the Gulf War, DoD activated Stage I of the Civil Reserve Air Fleet 10 days after the start of deployments and did not mobilize Stage II until five months later. The authors of the MRS BURU, however, assumed that in the future DoD would have access to Stage II planes much earlier in the first of two conflicts. In the event of a second conflict, the study assumed, decisionmakers would activate planes enrolled in Stage III. But based on DoD's experience in Operations Desert Shield and Desert Storm, some military officials have called the assumption about Stage II optimistic.

The MRS BURU used a more conservative approach in its assumptions about commercial sealift than about airlift. Although commercial shipping would deliver most sustainment supplies to two major conflicts, the study assumed that very few civil vessels would be used to move the initial surge of equipment and supplies from the United States. Defense officials made that assumption on the grounds that commercial ships might not be close enough to U.S. ports to begin a deployment at a moment's notice. The MRS BURU also assumed that DoD would use only U.S.-flag vessels. However, during the first three months of the Persian Gulf War, DoD relied extensively on both U.S.- and foreign-flag charter vessels.(10)

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Access to Airfields and Ports

Because of the distances involved in deployments to either the Persian Gulf or the Korean Peninsula, the Air Force uses bases in foreign countries so it can refuel airlift planes and change aircrews en route. Constraints on access to such bases can delay airlift operations. During the Gulf War, for example, three European bases--Zaragoza, Torrejon, and Rhein-Main--sup-ported 61 percent of U.S. airlift traffic.(11) But several of DoD's en route bases are no longer available, and it is uncertain whether the United States will have the same degree of access to alternative bases.

Airlift also operates more efficiently when planes can land at a staging base--a stop in or near the theater of operations where aircrews can rest while fresh crews fly the planes back for their next mission. During the Persian Gulf War, U.S. Central Command denied the Military Airlift Command (MAC) access to a staging base in the theater.(12) Instead, MAC added extra members to each crew so they could fly longer missions from en route bases in Europe to the Gulf region and back. Unfortunately, the larger aircrews meant that those personnel used up their maximum number of flying hours more quickly.(13) One study of airlift operations concluded that when access to aircrews is limited, the lack of a staging base can reduce strategic airlift capacity by 20 to 25 percent.(14)

Some military analysts have argued that the MRS BURU uses fairly optimistic assumptions about access to infrastructure, such as en route and staging bases, that would support airlift operations. If that is true, airlift deliveries might take place more slowly than planned. The MRS BURU also assumes that the Navy would not need to clear mines from ports or choke points like the Strait of Hormuz before sealift ships could complete their deliveries. Yet if that circumstance occurred, it could significantly slow the pace of a major deployment.



Time Between the Two Conflicts

Another critical assumption is the amount of time separating two major regional contingencies. Some analysts believe that in order for an aggressor to take advantage of U.S. involvement in one contingency, the conflicts would need to be between one and three months apart.(15) For the MRS BURU, that assumption was not left to the discretion of the study's authors; it was specified in the Administration's Defense Planning Guidance.

According to a 1993 study by RAND, strains on tankers and airlift planes would prevent the United States from prosecuting a second conflict successfully if the two were separated by fewer than three weeks.(16) Similarly, defense officials have argued that the sealift requirements set in 1992 (and reiterated in the MRS BURU) would be insufficient if DoD actually found itself sending equipment to two major conflicts at the same time rather than consecutively. And without sufficient time between the two conflicts, military officials might not be able to regenerate the Army's set of afloat prepositioning equipment. Clearly, separation time is a variable that can have significant implications for strategic mobility requirements.


1. "U.S. At 'High Risk' of Being Unable to Carry Out Two-War Strategy Until 2006," Inside the Pentagon, September 22, 1994, pp. 1, 6.

2. "Final Draft of Mobility Requirements Study Update to Go to Services," Inside the Pentagon, November 3, 1994, p. 3.

3. Department of Defense, "CENTCOM Theater Update," background briefing by a senior defense official, October 16, 1995 (available through DefenseLINK News at http://www.dtic.mil/defenselink/news/ Oct95/x101695_xback-a1.html).

4. David Kassing, Army and Marine Corps Prepositioning Programs: Size and Responsiveness Issues, PM-378-CRMAF (Santa Monica, Calif.: RAND, April 1995), p. 25; Douglas Jehl, "U.S. Ships Steam to Gulf in Response to Iraqi Move," New York Times, January 30, 1996, p. A-6.

5. Untitled news briefing by Department of Defense spokesman Kenneth H. Bacon, ATSD/PA, January 30, 1996 (available through DefenseLINK News at http://www.dtic.mil/defenselink/news/Jan96/ t013096_tbb0130.html).

6. Michael R. Gordon and Bernard E. Trainor, The Generals' War: The Inside Story of the Conflict in the Gulf (Boston: Little, Brown, 1995), pp. 14-20, 26.

7. Richard K. Betts, Surprise Attack: Lessons for Defense Planning (Washington, D.C.: Brookings Institution, 1982), p. 18.

8. John Lund, Ruth Berg, and Corinne Replogle, An Assessment of Strategic Airlift Operational Efficiency, R-4269/4-AF (Santa Monica, Calif.: RAND, 1993), pp. 30-31.

9. Thomas McCaffrey, Ready Reserve Force Contingency Crewing Requirements Study (Alexandria, Va.: McCaffery & Whitener, December 15, 1995), p. ES-1.

10. Ronald Rost, John Addams, and John Nelson, Sealift in Operation Desert Shield/Desert Storm: 7 August 1990 to 17 February 1991, CRM91-109 (Alexandria, Va.: Center for Naval Analyses, May 1991), p. 30.

11. Lund, Berg, and Replogle, An Assessment of Strategic Airlift Operational Efficiency, pp. 81-82.

12. The Military Airlift Command was renamed the Air Mobility Command on June 1, 1992.

13. To help ensure safety, the Air Force normally limits aircrews to flying a maximum of 16 hours per day, 125 hours per 30 days, and 330 hours over 90 days. During Desert Shield, those limits were raised to 18 hours per day, 150 hours per month, and 400 hours per 90-day period.

14. Lund, Berg, and Replogle, An Assessment of Strategic Airlift Operational Efficiency, pp. 31-35.

15. Michael O'Hanlon, Defense Planning for the Late 1990s: Beyond the Desert Storm Framework (Washington, D.C.: Brookings Institution, 1995), p. 7.

16. Christopher Bowie and others, The New Calculus: Analyzing Airpower's Changing Role in Joint Theater Campaigns, MR-149-AF (Santa Monica, Calif.: RAND, 1993), p. xix.


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