IN THE THIRD WORLD, the development of military missiles is progressing rapidly. Several of those countries now have the capability to produce missiles with considerably more than battlefield range. While the United States and the Soviet Union have cooperated effectively to slow the spread of nuclear weapons, they have made no parallel attempt to deal with missiles. Last April this country joined with six of its allies to restrict the sale of missiles capable of carrying nuclear warheads. That was an important initiative, but the Soviets have not yet joined it -- and, in any event, not all of the Third World is dependent on other countries' help.

Sen. Dan Quayle, who is drafting legislation to improve American control of missile exports, recently asked the Congressional Research Service to bring up to date its inventory of developing countries' progress in the field. India, which has launched two satellites with its own rockets, is by far the most advanced. But Brazil, as CRS describes it, is a more disquieting case. It has a large and sophisticated aerospace and arms industry and, unlike India, it has made itself a major exporter of armaments. Currently its two largest customers for military hardware are Iraq and Libya. CRS notes the "persistent rumors" that Libya has in turn been shipping some of its Brazilian weapons to Iran. Brazil's wide-open export policy is taking on deeper implications with the advance of its work on missiles.

Brazil is now testing a weapon said to have a range of 180 miles and a payload of a ton. CRS notes the reports that its builders demonstrated it to an Iraqi delegation late last year and expect to have it operational by 1990. They are also working on a version with a 750-mile range, as well as an anti-ship cruise missile.

Israel possesses a formidable arsenal of missiles, several of them capable of carrying nuclear warheads. One missile was tested last spring over the Mediterranean at a range of more than 500 miles. South Korea has evidently begun production of a surface-to-surface weapon based on adaptations of the Nike air defense missiles supplied to it by the United States.

The world properly devotes vast attention to the arms control negotiations between this country and the Soviet Union. Less wisely, it doesn't bother to take much notice of the arms races under way elsewhere in the world. They are proceeding with little restraint by arms control agreements except in regard to nuclear weapons -- and the countries most proficient in building missiles are usually the same ones that have refused to sign the Nuclear Nonproliferation Treaty.