Ballistic missile club is losing exclusive status. AFTER THE SUMMIT

When Brazil or India announces that it has launched space or atmospheric experiments using home-grown rockets, it's often seen as a sign of progress. But others look at those same rockets and quickly point out that a vehicle that can launch a 1,000-pound satellite can also send conventional, chemical, or nuclear weapons hurtling toward a longstanding enemy.

As a national-security concern, ``ballistic missile proliferation is right up there with nuclear proliferation. The two are becoming interlinked,'' says Andrew Goldberg, a national-security studies fellow at the Georgetown Center for Strategic and International Studies. ``Ballistic missile proliferation will be one of the key areas of technical tension in the 1990s.''

Not surprisingly, the initial nuts and bolts of missile technology, as well as the know-how to implement it, have come largely from the US and the Soviet Union, according to the Congressional Research Service (CRS), which has produced two reports in the last 20 months on the topic.

Both superpowers have sold short-range military missiles to some of their client states, especially in the Middle East, according to the CRS. The missiles have ranges from about 100 to 500 miles, depending on the type, and varying degrees of accuracy, depending on what guidance system, if any, is used.

Besides acquiring missiles designed specifically as surface-to-surface weapons, technologically advanced countries can modify other types of missiles for that use. For example, the CRS notes that South Korea modified US Nike Hercules antiaircraft missiles for use against ground targets, then used that experience to develop its own surface-to-surface weapon with a range of between 300 and 400 miles.

But the sale of military missile systems to countries not considered major military powers makes up only part of the picture. Concern is also growing over the ability of countries such as India, Brazil, Argentina, and Israel to loft rockets they've built themselves. Many of the countries involved are also states believed to be standing on the threshold of building nuclear weapons.

In Israel's case, the missile in question, the Jericho II, was designed specifically for military use. Unofficial reports give the missile a tested range of 600 miles and a potential reach of 900 miles. This would bring under its shadow some Soviet oil fields and naval bases as well as all Arab capitals. Iraq recently claimed to have tested its own surface-to-surface missile with a range of 400 miles, which would bring Israel well within range.

In other instances, the rockets are ostensibly for civilian space research and satellite launches. The nations involved have received aid through science and technology exchanges with other countries.

The two developing countries with the most advanced space programs are India and Brazil. According to Leonard Spector, a proliferation specialist at the Carnegie Endowment for International Peace, both nations have received significant help from Western countries, especially in critical areas such as guidance and propulsion.

As these and other nascent space efforts advance, analysts say, the countries involved become potential sources for the further spread of missile technology. Of particular concern is Brazil, which is already doing a brisk weapons business. The CRS notes that Brazil produces 80 percent of the weapons it needs, which amounts to only 10 percent of its total weapons production. The balance is sold overseas - with Libya and Iraq its two largest clients. Brazil places few if any restrictions on the end use of weapons it sells abroad.

Unlike efforts to slow nuclear proliferation, there is no international treaty affecting ballistic missile proliferation. The closest any nations have come is a missile technology control ``regime'' signed in April by the United States, Canada, West Germany, France, Italy, Japan, and Britain. It sets forth guidelines on missile-related technology export controls. The goal is to slow the spread of missiles capable of hurtling payloads greater than 1,000 pounds to distances greater than 480 miles.

Although the regime is only eight months old, ``we have evidence that the export restrictions are starting to bite,'' says a US Defense Department official familiar with proliferation issues. He declined, however, to give specifics.

One nagging question for some in Congress is the amount of effort spent on applying and monitoring the regime. Sen. Dan Quayle (R) of Indiana, who is a strong supporter of the Strategic Defense Initiative and efforts to develop antitactical ballistic missile defenses, tacked an amendment onto the defense authorization bill that President Reagan signed last week asking the Defense Department to report back by Feb. 1 of next year on how many people it has working on the regime and how adequate it feels its effort is.

At the same time, analysts say, it will take some skillful diplomacy to persuade other nations to adopt the regime as well as to discourage countries from building up their own missile arsenals. Indeed, they add, where missile capabilities pose a direct threat to US armed forces abroad, it may even be necessary to use military force to destroy installations.