WASHINGTON — IT used to be so simple: The US military's goal was to ward off the Soviet threat. But since the end of the cold war, US armed forces have been toting water for Rwandan refugees, ''restoring democracy'' in Haiti, and even aiding the decommissioning of Soviet missiles -- all in the name of peacekeeping.
But only last week, in its National Military Strategy statement, did the Pentagon formally add ''peace engagement'' to the principal missions of the US armed forces. By doing so it sharpened the debate over post-cold-war military and foreign policy and raised the ire of some Republicans in Congress.
Outlining the Pentagon's view of the threats facing the US, the Joint Chiefs point to a range of rising dangers including regional conflicts and the proliferation of weapons of mass destruction and conclude that the strategy of a shrinking US military must be one of ''selective and flexible engagement.''
While the Pentagon's top priorities are still nuclear deterrence and the ability to fight and win two near-simultaneous regional conflicts, the Joint Chiefs say, American forces must also be able to cope with ''a broad range of potential challenges.''
Activities designed to address such challenges by enhancing ''regional stability'' include: peacekeeping; humanitarian missions, such as carrying food to Sarajevo; military-to-military contacts, such as joint maneuvers with former Warsaw Pact nations; and other noncombat activities.
The new document appears to reflect what is already reality: the Clinton administration's use around the world of US troops in peacekeeping and other noncombat operations. ''It seems ... that we are in a period now where we are able to use military power in ways that we could not in the cold-war era,'' says a senior military official.
That conclusion will not sit well with congressional Republicans, who are pushing bills to restrict or terminate US participation in UN peacekeeping operations. The House of Representatives passed one version of the legislation last month, and Senate majority leader Bob Dole (R) of Kansas is sponsoring a measure with some similar provisions. Senior administration officials want President Clinton to veto any version that passes.
Republicans accuse Mr. Clinton of failing to consult Congress before sending US forces on UN operations that have no bearing on national interests. The administration counters that the GOP seeks to infringe on the executive branch's constitutional stewardship of military and foreign policy. Clinton says Republicans have a ''neo-isolationist'' agenda that is also embodied in their determination to cut back US foreign aid.
The dispute is shaping up as a defining issue in the 1996 presidential campaign.
Conservatives say that peacekeeping and humanitarian missions like those in Bosnia, Rwanda, Somalia, and Haiti hurt military readiness, because they sap the Pentagon's operations and maintenance budget. A GOP Senate staffer calls the strategy ''incongruous,'' because the Pentagon has not budgeted for such activities. ''There is the issue of paying for it and paying for it too dearly,'' he says.
As the US military undergoes a post-cold-war ''build-down,'' noncombat missions also divert troops from training for their traditional war-fighting role, critics charge. ''Everything in the military flows from strategy. If you make [peacekeeping] part of your strategy, you now have to devote physical and psychological resources to it. This is a further watering down of the military,'' says John Ludoy of the conservative Heritage Foundation here.
Andrew Krepinevich, director of the independent Washington-based Defense Budget Project, says that as resources dwindle, ''the questions are: How are they going to adapt? How quickly are they going to do it? And what are they going to sacrifice to do it?'' In the end, ''They are going to face some real hard choices.''