The SDI debate is similar to the great anti-ballistic-missile debate that so occupied Americans in the late 1960s in that mighty passions are engaged. But the SDI debate is very different in that there is an absence of a weapon-deployment program to advance or criticize.
This lack of a definite and detailed subject to debate has liberated the gladiators of theory from much of the discipline of evidence. Disingenuous though it may appear, it is not an exaggeration to claim that no one knows today which, if any, defensive-weapons technologies will be deployed, for what purposes, at what cost or over what span of years. When specific program details are missing, debaters are tempted to provide the ones that they prefer--either to promote or denigrate.
There is nothing inherently fanciful or quixotic about the idea of strategic defense. SDI is not in pursuit of the equivalent to an anti-gravity device. The history of technology, the progress achieved to date on a wide variety of technologies relevant to strategic defense, and plain common sense suggest that defense is feasible--with the unknowns pertaining to time, cost and quality of performance required.
By and large, U.S. critics of strategic defense have ceased to attack the vision of it that lends itself most easily to assault or even ridicule. The debate has shifted focus from exclusive concern with a hypothetical perfect "astrodome" defense of the United States and its allies to include jobs that even many critics admit to be technologically doable, such as the reliable protection of military assets. It should be recalled that, in the 1983 speech in which he first advertised his commitment to strategic defense, President Reagan spoke of rendering nuclear-armed ballistic missiles "impotent and obsolete" but did not state any requirement to intercept every Soviet nuclear warhead.
The strategic policy case for SDI includes the thesis that if relevant technologies sustain their current promise the result should be a process of technology-driven arms control. The Soviet Union is not going to waste scarce economic assets on the further proliferation of weapons that cannot achieve militarily useful goals. The SDI research program seeks to place a lid over the Soviet Union (and the areas where Soviet nuclear-ballistic-missile submarines could be deployed) as well as a roof over Western countries. Western strategic defenses capable of threatening Soviet missiles in their boost or very early mid-course phases of flight trajectory would hold missiles at risk regardless of their missions.
While everybody, it would seem, favors the conduct of research on strategic defense, only SDI proponents are willing to pay the entry price necessary if answers are to be found in the reasonably near term to critical questions of technical feasibility. The feasibility of wrecking Soviet theater-nuclear and strategic war plans through the active defense of weapons, forces, military facilities and even key transportation and communication centers is not seriously in dispute today. The deterrent effect on Soviet minds of denial of assured access to particular NATO-European or U.S. targets should be prodigious. Confronting Western defensive weapons of very long reach, Soviet military planners would not know how heavily, or even whether, particular targets were defended.
The Soviet Union has a rather old-fashioned view of what deters--one that focuses on prospective utility in combat. Strategic nuclear disarmament will be attractive in Moscow when its strategic weapons lose military and political value. Only through strategic defense is the West likely to provide the Soviet Union with a sufficient rationale for large-scale nuclear disarmament, and only in the context of thickly deployed defenses could the West accept the risks of Soviet non-compliance with a disarmament treaty.
SDI opponents are running out of theoretical arguments. The all-purpose claim that strategic defense would be destabilizing is increasingly acknowledged by the critics to be improbable, unless the Soviet Union unilaterally deploys new defenses in addition to its huge strategic offensive arsenal. In one debate after another SDI critics have failed to show why Western deployment of missile defenses, initially having the effect of protecting strategic offensive forces, would incline Soviet leaders to attempt a first strike. Even if they would anticipate doing better by going first rather than going second, why would they expect to fare well enough for such an attack to be the preferred policy choice? This key question remains unanswered.
On technical issues SDI critics have lost ground steadily since 1983. Such pet countermeasures of the critics as "space mines," "fast-burn" rocket boosters, fake boosters and a host of others have been shown, theoretically at least, to be impractical against a strategic defense that would be layered to attack missiles in different phases of flight and would employ some very different kill effects.
Over all, the SDI critics have not scored many points. The variety of instability charges and the allegation that a period of defensive transition would be very dangerous are gradually being dropped by the more competent critics. The claim that SDI damages arms control falls away when one adds the qualifier (to arms control) "worthy of the name."
Meanwhile, in the technical sphere the SDI research program is making progress more rapidly than the critics can rewrite their arguments. There may be some show-stopping issues for SDI, but they certainly have not appeared yet.