WHAT DID the Mariel Cubans who rioted at Oakdale and Atlanta achieve? Now that the siege has been lifted at both institutions and all the hostages have been released unharmed, there will be a lot of Monday morning quarterbacking and probably some criticism of the authorities for making any kind of a deal at all with the detainees. That criticism would be misplaced.

Under the terms of the agreements made at both the Oakdale and Atlanta facilities, each case will be reviewed before a single detainee is returned to Cuba. This is both fair and sensible. It had always been assumed that not every single one of the detainees would be returned. There are thousands of Mariel Cuban offenders in custody across the country, and Fidel Castro has agreed to take back only 2,500. That figure is not a quota or an obligation on the United States, it is a ceiling. In the review process that will now begin -- for many inmates, this will be a second review -- some will be given another opportunity to live in this country. All those who had been scheduled to be released before the riots will be released, as will many others. Those who are determined to be excludable because of the seriousness of their offenses will be allowed to go to any country that will take them -- this opportunity is available to any alien being deported -- but if such arrangements cannot be made, they will be returned to Cuba. These are not substantive concessions but a clarification of the process that was contemplated from the beginning. The rioters did not win automatic release, a promise that none of them would be deported or the kind of judicial hearing complete with court-appointed lawyers that they sought.

Was it irresponsible to agree not to prosecute detainees for the physical damage done during the riots? No, that would have been pointless. Further prosecutions and incarceration in American prisons would be costly and counterproductive when the government's real objective is to send the detainees home.

It is hard to know whether the disturbances could have been avoided altogether if there had been better planning. After all, the agreement with Cuba that sparked the uprising had provoked no violence when it was originally negotiated in 1984. Notwithstanding what might have been done before the siege, once it began Justice Department officials managed the situation well. Principle was not sacrificed for a settlement, and violence was not used to achieve it. Except for one minor incident, the hostages were unharmed. One detainee was killed during the disorder, but not by government forces. Cool heads prevailed all around, and patience paid of