President Reagan declared this week that ''our military forces are back on their feet and standing tall.'' Yet there remain serious questions about how long those forces could stand tall in the event of extended conflict.
There is no doubt that under Mr. Reagan the United States armed services have undergone unprecedented modernization as each branch rushes to buy the newest weapons. As a portion of the total defense budget, procurement is growing much faster than other categories.
But critics warn that this rearmament may be coming at the expense of the less flashy items it takes to sustain combat should a major war break out.
''Logistics in the Department of Defense is a major neglected area that could be a real problem in an emergency,'' Frank C. Carlucci said recently. Mr. Carlucci was Defense Secretary Caspar W. Weinberger's deputy until he returned to private business last January.
The Congressional Budget Office has reported that recurring operating and support costs for weapons like the M-1 tank could be as much as 41 percent higher than the tank it is replacing, well above Army estimates. And a recent General Accounting Office (GAO) investigation found that the Navy's carrier battle groups are suffering in combat readiness because of shortages in spare parts and munitions.
In its Pentagon budget request for fiscal year 1984, the Reagan administration asked for a rate of increase in new weapons purchases that was nearly 50 percent higher than the request for operations and maintenance (O&M) funds. And almost 40 percent of the projected 1985-89 increase in defense spending is allotted to weapons procurement, compared with 26 percent for O&M.
''The procurement account now absorbs the largest single share of (defense) budget authority,'' states a recent report by Common Cause.
''Procurement is gravely overfunded,'' said Eugene Carroll, deputy director of the Center for Defense Information and a retired US Navy rear admiral who once commanded an aircraft carrier. ''The whole strategy is to front-load the budget as long as Congress will go along with the money for the new systems on the assumption that when you finally get all of that hardware, somebody'll have to pay the bill to maintain it.''
While complaining about the size of the defense budget, Congress this year approved virtually every major weapons system. Pentagon officials and other analysts note that when lawmakers cut military spending, it is usually in areas affecting readiness. This is because such items as training do not have the political constituency enjoyed by tanks and planes, and because the savings from opertions and maintenance are immediate.
In response to the recent GAO report on Navy ships and aircraft, Vice-Adm. Carlisle Trost, director of Navy program planning, called readiness and sustainability today ''better than it's been in my 30-plus years in the Navy, and improving.''
''I don't think it's valid to say we've put so much money into hardware procurement . . . that we have undercut readiness,'' Admiral Trost told Pentagon reporters. Referring to the GAO report, he said, ''Lots of the things that they said were wrong have been corrected.''
At the same time, he acknowledged that in aircraft readiness ''we have fallen short of the goal we've established because of lack of adequate funding for spare parts and repair in recent years.'' At the moment, he said, ''just under half of our aviation units'' are considered fully or substantially mission-capable. But he added that Congress is at least partly to blame, and noted that in time of war some factors (such as certain safety features) would be ignored in considering which planes to send into combat. Among other things, the GAO noted that of the 14 aircraft carriers, only eight would meet combat-readiness requirements a month after the start of a war without shifting ''significant amounts of material . . . from shore stations and training squadrons.''
Part of this no doubt has to do with a shift in naval strategy under the Reagan administration from primarily sea-lane protection toward ''maritime superiority.'' This is one reason the Navy's inventory objective for munitions for the current fiscal year is $68.1 billion instead of the $19.7 billion planned for by the Carter administration - and why it is tougher these days to keep the Navy, and the other services, fully stocked with wartime supplies.