More talk about the draft; Uncle Sam wants . . . who?

Just as Uncle Sam is about to start cracking down on young men who have failed to register for the draft, fresh questions and concerns are being raised about this country's all-volunteer military forces.

In a report released today (June 29), the Atlantic Council of the United States (a bipartisan group of military and civilian experts) concludes that the all-volunteer force (AVF) as constituted and operating is not sufficient to meet US military manpower needs. The council judges that a resumption of the draft may be necessary before the end of the 1980s.

While not going this far, the Brookings Institution this week also questions the makeup of the AVF, especially the disproportionate number of blacks in Army and Marine Corps units. Here, the armed services are lauded for ''pioneering racial intergration.'' But, reflecting larger social and educational problems, nonwhites still tend to be concentrated in clerical, service, or supply fields while whites are more likely to receive technical or craft skills, the report concludes.

All of this comes just a few days before the US Justice Department is expected to begin prosecuting the first of more than half a million young men who have failed to register for the draft. The US Selective Service System has referred 160 cases to the Justice Department, mostly conscientious objectors who have told the federal government they are refusing to register. Such action is a felony, carrying with it up to five years in prison and a $10,000 fine.

For the moment, Pentagon and Selective Service officials are upbeat in their views of the issue. The registration compliance rate is now above 90 percent. All of the armed services are meeting or exceeding their recruiting goals, reenlistment rates are improving as well, and the quality of recruits (as measured by test scores and the number with high school diplomas) continues to rise.

But this may mask longer-range problems, many military manpower experts believe. These include the likely effect of economic recovery on recruiting and retention, the dwindling pool of military-age persons, a need for even better qualified people as the military becomes more technologically advanced, and the racial imbalance in the armed forces.

In addressing this last point, the Brookings Institution notes that while blacks compose 11 to 12 percent of the general US population, they make up 22 percent of the Marine Corps and 33 percent of the Army. Put another way, 40 percent of eligible young black men are in military service compared with less than 15 percent of whites.

Many experts therefore assume that blacks would suffer disproportionately high casualties in the event of conflict, a situation Brookings scholars find ''immoral, unethical, or otherwise contrary to the precepts of democratic institutions.''

In taking a broader look at US military manpower, the Atlantic Council's military service working group (drawn from business, labor, government, education, and youth as well as the military) warns that ''American military active duty strength entering the 1980s is at its lowest ebb since 1950.'' Among its findings, this group recommends a new GI Bill of more generous educational benefits, a greater role for women in the armed services, an extension of reserve service obligation from six to ten years, and appointment of presidential commissions to plan for a future military draft or national service program.

Noting the increasing gap between NATO and Warsaw Pact conventional this group reports the ''significant probability that the requirements of peace and security will compel this country to resume the draft, perhaps by the mid-1980 s.''

President Carter and his national security staff had concluded that the draft would have to be instituted and would have done so in January of this year, according to former White House sources. There is a growing sense outside the administration (even on Capitol Hill) that there may well have to be some form of compulsory national service, but many political analysts have concluded that the question cannot be directly faced until after the 1984 election.