Not all military threats are created equal. Some are publicized but unlikely. Others get scant attention but are quite real.

Take missile proliferation. Its most recent manifestations -- the cruise missile attack against the USS Stark and the Chinese sale of Silkworm cruise missiles to Iran -- are bad enough.

Yet worse may be in store: smaller nations are developing ballistic missiles, and some will soon export them.

The Senate Armed Services Committee got an early warning about this when it held hearings in April 1986 on the emerging tactical ballistic missile threat in Europe, Asia and the Middle East. At that session, I released a Congressional Research Service report detailing the spread of missile technology to the Third World. The report examined missile development programs in India, Brazil, Pakistan, Argentina, Israel, South Korea and Taiwan, as well as existing missile arsenals in Syria, Egypt, Iraq, Libya and North Korea.

That was a year ago. Now no fewer than six new, large military ballistic missile programs are under way -- and Libya and South Africa have programs of their own. Specifically, since April 1986:

Argentina has successfully tested its first solid-fuel rocket and announced plans to mass produce a longer-range version in late 1987 capable of reaching the Falklands.

Brazil has revealed plans to flight test a theater ballistic missile in mid-1988. Developed for export by the firm Avibras, this missile would have characteristics identical to Soviet missiles now deployed in Europe and in the Middle East. A rival Brazilian firm, Engesa, has announced it will compete by extending the range of the ballistic missile it is now testing.

Libya has begun development of a tactical ballistic missile to replace the Soviet missiles it actually fired against Italy last year.

South Africa has announced plans to develop long-range military missiles by the firm Armscor.

Taiwan has begun development of a ballistic missile that could reach Canton, Shanghai and Nanking.

India has announced it will test a variety of tactical missiles and intercontinental-range rockets in 1987. Meanwhile, our exports of supercomputers and antenna equipment have been held up for fear that they might be used in India's military missile effort.

Pakistan has begun a rocket program of its own in response to India's activity.

These are the facts. The question is, what are we going to do about them?

Much was made earlier this year of the missile technology export control agreement President Reagan reached with Canada, France, Germany, Japan, Italy and Great Britain. In fact, this ban on specific dangerous missile technology exports was generally praised.

There's been silence, however, on just how far we intend to promote it diplomatically. Merely controlling the missile exports of our closest allies is hardly going to do the trick. The problem is much bigger. For starters, none of the smaller nations now developing military ballistic missiles is even covered by the accord. Nor are the two largest missile technology suppliers -- the People's Republic of China and the Soviet Union. Getting all of these nations signed on should be priority No. 1.

Our second priority should be to implement the obligations we've taken on. Right now the United States has only two experienced full-time government people working missile proliferation export control issues. Yet at least 80 full-time people work on nuclear export controls and well over 250 on East-West technology export control. If we are serious about enforcing missile exports controls, comparable numbers of experienced staff must be hired to monitor missile activities.

These steps should buy us time. With time, three other things can be accomplished.

First, we need to renew our security assurances to some of the problem nations listed above. Taiwan, South Korea, Pakistan and Israel, in particular, need to recognize that they have more to gain from maintaining their security ties with the United States than from developing offensive ballistic missiles of their own. Second, we need to make it expensive for fledgling nations to have missile forces. We should make it very clear that their emerging missile forces will remain extremely vulnerable to highly precise, stealthy, conventional long-range cruise missiles unless they spend heavily for air defenses, missile hardening and mobile basing to protect them.

Finally, we need to develop anti-tactical missile defenses to protect our forces and allies abroad. The better these defenses are, the stronger we can make our alliances and the further we can reduce other nations' attraction to cruise or ballistic missiles as a quick, cheap way to increase their regional influence.

This last point is critical. So long as nations think they can make a quantum jump in military power easily by acquiring missiles, many will try. What we've got to do is make sure that missile technology is difficult, expensive and militarily counterproductive for them. If we don't, this technology will spread faster than we can cope with it -- so fast that it will make our current crisis in the Persian Gulf the least of our missile woes.

The writer is a Republican senator from Indiana and a member of the Armed Services subcommittee on strategic forces and nuclear deterrence