America has five years left.

AMERICA HAS FIVE YEARS LEFT

TIME IS running out for the UnitedStates. Just two months ago, Robert Gates, Deputy Director of the CIA, confirmed reports that the Soviets were constructing three more huge phased-array radars in the western USSR. These mammoth radars, each as large as a football field, close the final gap in the network of radars guarding the missile corridors into the Soviet Union.

Some analysts say the Soviet radarnetwork is intended for early warning. However, the radars have a combination of size and power that goes far beyond early-warning requirements. They have the range and angular precision needed to get an accurate track on an oncoming warhead, figure out which target the warhead is headed for, and alert ABM launch sites in the warhead's path so they can send up missiles to intercept it. In fact, they have all the properties of "battle management' radars designed for an ABM defense of Soviet territory.

The new radars and their fellows--the complete ABM radar network has nine--are the long poles in the Soviet ABM tent. They take several years to design and five or six years beyond that to build. The Soviets must have started working on the first of them around 15 years ago, while they were still negotiating the ABM Treaty.

Mr. Gates also confirmed the existenceof Soviet production lines for manufacturing large quantities of ABM equipment. That means volume production of the intercepting missiles that destroy oncoming warheads, the launchers that send these missiles into battle, and the small "engagement radars' that point the missiles in the right direction to make an intercept.

Article I of the ABM Treaty sayseach side must promise not only that it will not deploy a nationwide ABM defense, but also that it will not "provide a base' for such a defense. The Soviet radar network and ABM production lines constitute a base for a nationwide ABM defense. This goes beyond isolated technical violations like the inland location of the Krasnoyarsk radar. It tears the guts out of the ABM Treaty.

The CIA report calls the SovietABM buildup "ominous,' with "awesomely negative implications' for American security. This is strong language coming from a senior CIA official. In the past the CIA has been conservative in its estimates of Soviet capabilities in the nuclear arena. Why is the CIA so alarmed now?

The answer is that this recently discoveredbuildup of Soviet ABM defenses has been going on in concert with the buildup of a first-strike ICBM arsenal. Mr. Gates writes: "Their heavy ICBM force is designed for the Soviets to strike first.' As a result of that missile buildup, the Soviets could, with half of their ICBM force, destroy essentially all our ICBMs plus a large fraction of our bombers, cruise missiles, and ballistic-missile submarines.

Little would be left of our nuclearforces for retaliation in the aftermath of a Soviet first strike. Destruction of U.S. military communications links would further diminish the effectiveness of the U.S. response. Against the ragged retaliatory strike the U.S. could launch after such an attack, the Soviet ABM defenses now under construction would be very effective.

The bottom line is that the SovietUnion is developing a lethal combination of a first-strike attack force and a defense against retaliation by U.S. ballistic missiles. That combination removes the ability of the United States to protect its citizens from nuclear attack. If Soviet plans come to fruition and the Soviets' nationwide ABM defense is deployed, the U.S. will have suffered the greatest military reversal in its history, with highly destructive consequences certain to follow.

HOW MUCH TIME do we have? Notvery much. The three new radars that close the gap in the Soviet network will be completed around 1991 or 1992. According to the CIA, the same time frame--the early 1990s--is also the best guess for deployment of nationwide ABM defenses in the USSR, constituting the final Soviet breakout from the ABM Treaty. That gives the U.S. about five years before our nuclear deterrent is emasculated.

A general understanding of this dangerunited the three authors of NR's recent special SDI update [Dec. 31] in their call for an early deployment of missile defenses. They pleaded for the immediate use of technologies in hand now, without "researching the problem to death,' as Jack Kemp put it. That means backing away from the laser and the particle beam as far as early deployment is concerned. These exotic devices are promising but they require more research. They will not be available in our time of greatest peril.

The technology we have in handnow is the "smart bullet,' a heat-seeking missile that homes in on its target like a snake stalking a rodent. Smart-bullet technology is relatively mature and ready to use. It is just an evolutionary development out of heat-seeking missiles (like the Sidewinder) routinely used in air defense.

Smart bullets can be fired at theirtargets either from launchers on the ground or from satellites in orbit. They have been tested against targets in space, including a ballistic-missile warhead, and are highly effective.

Congressman Kemp says we shouldmake use of this proven technology by putting up one hundred smart-bullet launchers (the number permitted by the ABM Treaty) as fast as we can. I made similar proposals last year, after talking with experts about the rapid progress being made in the smart-bullet technology, although my proposals involved more launchers and would not have complied with the treaty.

A great deal of work is going onin the SDI program on these smart-bullet defenses, with a view to meeting the Soviet first-strike threat at the earliest possible moment. However, the thinking on this matter in the SDI Organization, and on the part of Defense Secretary Weinberger, is a little different from what Congressman Kemp and I, among others, had proposed.

The Secretary and senior SDI managementhave concluded that an effective defense must include smart bullets based on satellites orbiting over the USSR, so that the Soviet missiles can be destroyed in their boost phase as they rise from their silos, before they release their warheads and decoys. In the judgment of these DOD officials, a space-based layer is essential because a massive Soviet first strike would send thousands of warheads and perhaps a hundred thousand decoys toward the United States. A "threat cloud' of those dimensions would confront the ground-based layers of our defense with an almost insurmountable challenge.

But if we can catch the ICBMs intheir boost phase, we get them with all their eggs in one basket. It doesn't matter how many warheads and decoys each ICBM carriers; we kill them all with one bullet. That greatly simplifies the problem for the ground-based layers of our defense.

The boost-phase defense, based inspace, also makes it difficult for the attacker to overwhelm our defense by concentrating his attack on high-priority targets, such as MX silos or the National Command Authority, because he cannot tell beforehand which missiles and warheads are going to get through and which will be shot down.

Congressional supporters of an earlymissile defense grant these virtues of the space-based layer but say that the pace of the Soviet move toward a nationwide ABM defense does not permit us the luxury of waiting until the space-based layer is available. We only have four or five years. We must go forward with what we have. Even if the initial, ground-based defense is only partly effective, it will introduce a large measure of uncertainty that will deter the Soviet leadership. Any factor that discourages the Soviet Union from using its first-strike arsenal is a big plus for American security.

I myself shared these views, andbelieved that we should go forward with a ground-based defense without waiting for the space-based layer. Then, quite recently, I was surprised to learn that it is not necessary to make this painful choice. Several independent studies indicate that a space-based layer can be put in place in the same time frame as the ground-based layers. This result came out of the deliberations of the technical panel on missile defenses convened by the George C. Marshall Institute. The five members of the panel have more than 160 years of combined experience in defense and space. Lieutenant Colonel Worden's article in the NR special update confirms their finding.

The Marshall Institute panel concludedthat the technical situation will allow deployment of a space-based defense layer starting in six and a half to seven years from the time the political decision is made to go forward. Deployment could start in 1993 or 1994, if the decision to proceed were made this year.

The complete defense will have threelayers, the other two layers being ground-based. One of the ground-based layers--the so-called ERIS layer, which uses smart bullets to intercept oncoming warheads high above the atmosphere--has a more mature weapons technology than the other layers and can be deployed even sooner, perhaps as early as five years from the time of the political decision to proceed. That means deployment of the ERIS layer might start in 1992 if the decision to deploy is made this year.

As congressman Kemp and LieutenantColonel Worden point out, an incremental approach to the deployment of the full defense, starting with deployment of the ERIS layer in 1992, would be valuable. It would provide the earliest possible protection against accidental or irrational launches, and would also provide a useful degree of deterrence against limited attacks on key military sites.

But there is a great danger in deployingan ERIS layer before the rest of the defense. ERIS has limited effectiveness against a massive attack. If we deploy ERIS first and say it will be followed up in two years by a space-based layer, critics of SDI will conveniently forget the last half of the announcement. They will say, "See here, the Soviets can overwhelm that defense easily with more warheads and decoys. SDI isn't worth much.'

It's true. A defense without a space-basedlayer is very vulnerable to decoys and would provide a powerful incentive for the Soviets to develop large numbers of low-cost, lightweight fake warheads. A ground-based defense by itself would give us only a few years' respite. It is essential to follow up the ERIS deployment as quickly as possible with the space-based layer.

DEPLOYING ground-based defenseswithout a space-based layer would also be tentamount to handing military control of space over to the USSR. We know Soviet scientists are working very hard on lasers to destroy satellites in orbit. They are also working on lasers as a boost-phase defense against U.S. ballistic missiles. If we do not press forward as rapidly as possible with our own space-based defense, by the late 1990s the Soviets will be in a position to disrupt U.S. communications and reconnaissance satellites at will. By the end of the century, they may be able to keep the United States out of space altogether. They'll close the door and say, "You can't come in.'

We can no more survive as a nationwithout a military guarantee of free access to space than we could survive without a military guarantee of access to the world's oceans. We need space-based defenses as much as we need the U.S. Navy. That is why Gorbachev was so insistent on killing the space-based part of SDI in Reykjavik, and why the President was so insistent on preserving it.