The antiballistic missile (ABM) system could make a comeback because of the weapons President Carter and Soviet Leader Leonid L. Brezhnev have chosen for their nations' nuclear arsenals.
Carter has picked the MX missile and Brezhnev the SS18, both nuclear blockbusters accurate and powerful enough to destroy any intercontinental ballistic missile (ICBM) still underground.
To dodge the Soviets' bullet, so to speak, Carter has decided to make the MX a moving target. It will run back and forth in a covered ditch, something like a subway train. But such mobility does not guarantee the MX could survive a Soviet attack.
The Carter administration has promised to slide the roofs off the MX network of tracks and protective stations so Soviet satellites could verify that the United States had not deployed more missiles than the strategic arms limitations treaty (SALT II) allows.
Once this information is in hand, Soviet planners might well insist on deploying enough warheads to blow up the MX fortifications. The U.S. Air Force contends this would be a losing proposition from a cost standpoint but this may not deter the Kremlin.
In light of the unwillingness of U.S. leaders to give up on the idea of making land ICBMs invulnerable to surprise attack, the question for the 1980s and 1990s is likely to be: "What can we do to protect the MX missiles now that the Soviets have targeted them?"
An antiballistic missile (ABM) almost certainly would be advocated at this juncture, if not before. Some weapons specialists have never agreed that hitting a bullet with a bullet is impractical. And former defense secretary Melvin R. Laird described the ABM as the logical response to "first strike" weapons that today's Pentagon leaders cite as the rationale for the MX.
"With their large tonnage warheads," Laird told Congress in 1969 in referring to the Soviets, "they are going for a first strike capability - there is no question about that." He said the ABM must be built to stop Soviet SS9 missiles from blowing up our own.
Although the SS9 apparently did not live up to the expectations of either the United States or the Soviet Union, Defense Secretary Harold Brown recently said Russia's newer ICBMs will soon be able to destroy most U.S. missiles now deployed.
In short, the MX is a different response to the same threat Laird talked about in 1969. But the MX is just the latest response, not the final one, to Soviet "first strike, counterforce" weapons like the SS18.
On the Soviet side, land ICBMs will be threatened by both the MX, with each missile carrying 10 warheads of 335 kilotons each, and more accurate submarine missiles planned for the American arsenal of the 1980s and 1990s. An accurate submarine missile is especially difficult to defend against because it can fly in low from a short distance offshore.
Although the Soviets might follow the U.S. lead and make their ICBMs mobile like the MX, another option would be to improve the ABM which historically has been strongly backed in Russia.
On of the foundation stones under the SALT II agreement is the treaty signed in Moscow on May 26, 1972, limiting ABM systems on both sides. That treaty gives each party the right to withdraw after six months' notice "if it decides that extraordinary events releated to the subject matter of this treaty have jeopardized its supreme interests. . ."
Carter and Brezhnev, who are in Vienna to sign SALT II, have opted for building "counterforce" weapons specifically designed to destroy ICBMs in their silos. They are considered "first strike" weapons because it would make no sense to fire them at empty silos in a "second strike" attack.
The Congressional Budget Office, in a report this week on the MX, noted that the United States "might at some point find it more economical to develop a means to defend U.S., missiles" rather than to keep building more and more shelters to protect them against a growing arsenal of Soviet warheads.
"The advances that have been made in ballistic missile technology," the report said, "may make" and ABM defense for parts of the MX system "feasible."
Going back to square one is not what Carter and Brezhnev have in mind, of course, as they toast the SALT II agreement in Vienna. But recent history suggests that each new weapons makes the nuclear arms race harder to constrain.