313. Memorandum From Secretary of Defense McNamara to President Johnson1

I understand you were surprised by my comments at the Thursday, September 7, news conference on the so-called infiltration barrier in Vietnam.2 At fault may be my failure to acquaint you with the inquiries from the press which forced us to make a public statement. In this memo, I have summarized the current status of the project.

What the System Is. The term “barrier” being popularized by the news media is a misnomer. The anti-infiltration system will not be a wall nor a Maginot Line type of barrier. The system will consist of (1) an obstacle line across part of South Vietnam just south of the Demilitarized Zone (DMZ) and (2) an air-supported interdiction capability centered mostly in Laos. The initial segment of the obstacle line will consist of six strong points, three base camps, and about 8 miles of barbed wire, mines, detection devices and observation posts. This initial obstacle segment is to be installed by November 1, 1967. Thereafter, the obstacle line will be extended to about 15 miles.

The rest of the anti-infiltration system—the major part—will be the air-supported system consisting of air-delivered mines, warning bomblets, and sensor devices. These warning devices and sensors constitute the unique part of the system. When infiltration is detected, [Page 770] strike aircraft will be called in. The actual attacks will be carried out by units already in operation in Southeast Asia.

This air-supported system in turn has two parts, (a) an anti-vehicle system, and (b) an anti-personnel system. The systems differ in the types of warning devices and sensors employed as well as the geographic areas for employment. The anti-vehicle system will be concentrated in central Laos, with initial installation in November–December 1967. The anti-personnel system will initially be installed in eastern Laos, about a month after the anti-vehicle system. If necessary, the anti-personnel portion will be extended eastward from the Laos/SVN border toward the obstacle line.

Resources and Costs. The approved program of 525,000 personnel for South Vietnam included the manpower for the anti-infiltration system. The two year costs (FY 1967–68) are now estimated at about $780 million. Nearly 60 percent of these costs are for munitions which would have been procured in one form or another in any event. The remaining costs are for R&D, new sensors, and modification of existing aircraft to deploy and monitor the mines and sensors.

Why Is the “Barrier” Necessary. To counter the infiltration of men and supplies from North Vietnam, we have used air and sea power against North Vietnam; air power and ambush operations in Laos; and air, ground, and sea actions south of the DMZ. For the period September 1, 1966 to August 31, 1967, we flew over 40,000 attack sorties in Laos and over 50,000 attack sorties in the southernmost portion of North Vietnam. We have increased the U.S. fighting strength in the northern part of South Vietnam by more than 30 percent since December 31, 1966. Yet the infiltration not only continues but has increased. One of our impediments in interdicting the enemy has been our inability to locate him and concentrate our firepower. Any attempt to more precisely locate the enemy, accompanied by selective interdiction in depth, offers the potential to reduce his effectiveness.

Expected Benefits and Risks. We do not expect to stop infiltration cold. Dr. George Kistiakowsky, one of our consultants on the project, expects, however, that truck attrition can be increased two or three hundred percent. He thinks we may get thirty percent attrition against personnel. Our present personnel interdiction level is surely much less—recent prisoner reports indicate it may not exceed two percent. While the effectiveness of the system will not be known for three to six months, the new system will dramatize North Vietnam’s involvement in the war as well as our essentially defensive operations in South Vietnam. Furthermore, if effective at all, the components should be useful in other parts of Southeast Asia (or the world) where selective detection and strikes are desired.

To be realistic, Dr. Kistiakowsky’s forecasts may be optimistic. The system is comprised of numerous elements which must mesh well for [Page 771] effectiveness. Research, planning, production, and training are proceeding concurrently on many of the elements. Initial results may be degraded as a result. In addition, the aircraft delivering the mines and sensors, and monitoring the anti-vehicular and anti-personnel subsystems, may be vulnerable to significant attrition. There is the risk, too, that expectations for impressive early results will create clamor to substitute the new anti-infiltration system for other military measures.

The Military View. Opinion among the military ranges from General Wheeler’s advocacy and optimism to General Greene’s opposition. For the most part, the Chiefs and General Westmoreland look more favorably upon the idea now than they did a year, or even six months, ago. General Wheeler told the Stennis Subcommittee3 that he was “… almost positive that the sensors and munitions that we are developing will give us the capability of obstructing and disrupting the flow of men and material to the South.” General McConnell was less enthusiastic in telling the Subcommittee:4 “It will certainly contribute to some extent. I do not believe that it will contribute to the extent that the most enthusiastic proponents believe that it will.” General Greene said:5 “From the very beginning I have been opposed to the project. My feeling is that the job could be done by the addition of … troops operating on a mobile basis below the DMZ and supported by tremendous quantities of naval gunfire, air and artillery support.” General Westmoreland’s staff said in Saigon in July that “We hold high expectations that the system, providing it meets design specifications, will complement greatly our on-going anti-infiltration efforts.”

My Press Conference Remarks. Planning and development of this system have been underway for over a year. As work progressed, the amount of outside inquiry increased. As the Chiefs’ responses indicate, Senator Stennis and the Preparedness Subcommittee showed particular interest in the project and there were leaks from the Committee to the press. General Westmoreland wired on August 26, 1967, that, because of increasing media interest, public affairs guidance for the project would be required in the near future. Press comment increased during the first week of September, culminating in Joseph Kraft’s article from Saigon on the morning of my press conference. I was forced to reply—I chose to do so by a short statement. Copies of my statement and Kraft’s article are attached.6

Robert S. McNamara
  1. Source: Johnson Library, National Security File, Country File, Vietnam, 2D Barrier. Secret. The notation “L” on the memorandum indicates that the President saw it.
  2. At the September 7 news conference, McNamara outlined in the barest terms the obstacle system that would be installed along the DMZ, presenting the barrier as a means of avoiding stronger military action in Vietnam. He also stated that the final recommendations of the Stennis subcommittee amounted to a call for widening the war in Vietnam, and thus intimated that the barrier could avoid such a calamity. See American Foreign Policy: Current Documents, 1967, p. 987.
  3. In testimony on August 16.
  4. In testimony on August 22–23.
  5. In testimony on August 28.
  6. Neither printed. Kraft’s editorial asserted that the only benefit of the barrier would be an end to the bombing of the North and an opportunity for the opening of peace talks. See The New York Times, September 8, 1967.