A new study says the Soviet Union does not deploy big nuclear missiles all in northern regions closest to the United States, as is commonly believed, but instead has many in southern and far-eastern provinces aimed at targets all around the world.

This pattern is partly in response to the way U.S. nuclear weapons are deployed, to give the Soviets some means of answering the U.S. nuclear-armed aircraft based in Turkey, for example, and an ability to hit, as the study puts it, "the U.S. Strategic Air Command base in Guam; nuclear ammunition sites and naval bases in Guam, the Philippines and Hawaii." But it also gives Soviet missiles the ability to hit less likely targets in such places as Brazil and South Africa, the study says.

In addition, it has a defensive virtue from the Soviets' standpoint, in that it puts the Soviet missiles "out of normal range of many [American] Minuteman ICBMs," according to the study.

The study was done by John C. Baker and Robert P. Berman over the last five years and published this month by the Brookings Institution. It provides the first comprehensive public picture of the global Soviet nuclear missile force, its deployment and how it grew to what it is today.

It is supported by other analysts.

"The Soviets have a concept of global conflict, both intercontinental and regional, and have nuclear forces allocated to each," one analyst said yesterday.

There are targets not only in the United States but all of western Europe and other potential enemy countries. Also included are such military units as American aircraft carrier task forces that ply the Mediterranean Sea and other international bodies of water around the Soviet periphery.

That in part explains, this analyst said, why the Soviet Union has so many more missiles than the United States, all of whose nuclear ICBMs are aimed over the North Pole solely at the Soviet Union.

The Brookings study traces the historical development of the various Soviet missiles, pointing out that competing nuclear missile design bureaus turn out new rockets models much as Ford, General Motors and Chrysler turn out new cars in this country.

Historically, the primary target area for Soviet nuclear weaponry has always been western Europe.

The first Soviet missiles were intermediate-range rather than intercontinental, and even today, according to the study, the Soviets maintain mixed units armed with both types of nuclear missiles.

The rocket army around Moscow, according to the study, "has nearby as well as intercontinental targeting responsibilities."

Giant SS19 intercontinental missiles can strike European targets and, along with slightly smaller ICBMs such as SS11s and SS17s, the study says, "can cover most of the United States and all of Canada."

Older, solid-fueled SS13 missiles near Moscow, the study says, could attack American "early warning systems in Canada and Greenland."

To illustrate the worldwide reach of Soviet weapons, the study points out that the rocket units in the north have older SS4s and SS5 liquid-fueled missiles aimed at "targets throughout Scandinavia and into Iceland . . . and can extend . . . to Greenland."

The central rocket forces, armed with mobile SS20s, "can cover targets in central Europe, southern Europe, Near Eastern and Central Asian theaters and even reach China in the Far East."

The southern rocket army can hit "Turkey, Israel and Iran" with SS4s and Greece, North Africa and Saudi Arabia with SS5s, the study says.

One mid-1970s modification of the SS18, which gave it an 8,000-mile range, "permits coverage of areas as distant as South Africa and Brazil" from bases in the southern Soviet Union, the study says.

Not all the missiles designed by the various bureaus go into production.

And among those produced, few are built in large numbers. Thus the Soviets have a much larger number of missile types than does the United States.

For example, the Yangel design bureau built the SS9 in the late 1950s with a 25-megaton warhead designed to destroy large area targets. "But the size and expense of the SS9 probably precluded production at the levels needed to match the high deployment rate of the U.S. Minuteman force," the study reports. Only 308 of the giant missiles were deployed.

In the 1970s, the Yangel bureau came up with the SS18 as a replacement for the SS9. "One version of the SS18," according to the study, "with a single warhead was suitable for attacking such targets as U.S. Minuteman launch control centers, while other SS18 ICBMs carrying multiple warheads made it possible for the USSR to effectively extend its target coverage to the Minuteman silos for the first time."

Altogether, according to the study, there have been five modifications of the SS18, each with a different range or warhead configuration.

The Soviets have had their most difficulty in developing solid-fueled systems, both for land-based and sub-launched missiles. This program has been centered in the Nadiradize design bureau.

Its first attempt in the 1960s, the SS13 ICBM, ran into "serious technical problems," according to the study and only 50 were deployed. At the same time, two other solid-fueled shorter intermediate-range missiles, the SS14 and SS15, were tested and they, too, ran into problems. Only a few of each were deployed.

The next generation saw development of the SS16, which was to be a mobile, solid-fueled, three stage ICBM. It, too, developed problems and never was deployed.

Its first two stages, however, were turned into the SS20 intermediate-range mobile missile, some 333 of which have been deployed, according to Pentagon sources.

Now the Soviets are preparing to test a newer version of the mobile missile, and American intelligence experts expect it to have a varied range.