BECAUSE THE POTENTIAL OCCURRENCE OF A NUCLEAR TERRORIST INCIDENT HAS BEEN RECOGNIZED BY MANY PERSONS OF VARIOUS BACKGROUNDS, THE UNDERSTANDING OF THE THREAT REQUIRES EXAMINATION FROM SEVERAL PERSPECTIVES. ALTHOUGH SUBSTANTIAL DISAGREEMENT EXISTS ON THE NATURE OF THE THREAT, THESE ANALYSES EMPHASIZE THE POTENTIAL USE OF NUCLEAR WEAPONS BY INDIVIDUALS AND GROUPS, AND DO NOT ADDRESS THE CONCURRENT ISSUE OF NATIONS' NUCLEAR POWERS. LIKEWISE, THE ISSUE OF SEPARATING CREDIBLE TERRORIST THREATS FROM EMPTY BOASTING IS LEFT UNARTICULATED. NEVERTHELESS, MANY EXPERTS AGREE THAT WITH SUFFICIENT MONEY AND DEDICATION ANY GROUP COULD OBTAIN RADIOACTIVE MATERIAL JUST AS READILY AS THEY COULD BUY HEROIN OR ROB A BANK. SABOTAGE OF A NUCLEAR FACILITY, THEFT OF AN ATOMIC CARGO, AND EVEN CONSTRUCTION OF A USEABLE BOMB FROM PURLOINED MATERIALS ARE POTENTIAL DANGERS. SCIENTISTS OF GREAT SKILL COULD BE COERCED OR DRIVEN BY MISGUIDED IDEOLOGY TO WORK FOR OR ASSIST TERRORISTS. CONSIDERABLE SAFEGUARDS MAY BE REQUIRED TO PROTECT ALL NUCLEAR FACILITIES, BUT SUCH REQUISITE AUTHORITARIANISM CONTRADICTS THE CIVIL LIBERTIES OF MANY NATIONS. EXAMINATION OF PAST TERRORIST INCIDENTS AND OF THEIR PATTERNS OF WEAPONS ACQUISITION INDICATES THAT STATES COULD SUPPLY ATOMIC BOMBS TO DISAFFECTED GROUPS AND THAT ORGANIZED CRIMINALS COULD DIVERT NUCLEAR MATERIAL FROM INDUSTRIAL SITES. ADDITIONAL DISCUSSION CONCERNS THE MEANS OF PREVENTING INTERNATIONAL TERRORISM. APPENDED MATERIALS DESCRIBE NUCLEAR TECHNOLOGY AND LIST INCIDENTS OF THREATS TO FACILITIES. (TWK)