Once again the phrases come. Quagmire. Slippery slope. Endgame. Vital national interest. Global policeman. Exit strategy.
For policymakers - and for millions of Americans anxiously watching their countrymen at war in the Balkans - NATO's air attacks against targets in Yugoslavia raise profound questions about the US role in the world today.
Some of those questions are military, some are diplomatic, some are political or even very personal. But in light of America's military actions since the end of the Vietnam War, they all amount to this: Is there a new moral threshold for wielding power, for intervening forcefully abroad?
Harry Summers, a retired US Army colonel who teaches at the Army War College, notes a shift toward "peacekeeping" and "nation building" as rationales for using US military strength. Haiti, Somalia, and Bosnia are some recent examples.
But are these vital national interests?
White House policymakers, led by Secretary of State Madeleine Albright, believe so. Others are not so sure, even in a case like Yugoslavia, where other NATO countries are contributing about half the air power.
"Right now, the US armed forces are stretched to the breaking point and don't need another long-term peacekeeping commitment, especially one where our allies can handle the job," says Joseph Collins, a senior fellow at the Center for Strategic & International Studies in Washington and a former strategic planner at the Pentagon.
"If the Europeans want us to be involved in every facet of every operation in Europe," he adds, "they should be prepared to take some of the pressure off of our troops on the Arabian Peninsula or in other deployments."
The 1980s and 1990s have seen a series of US military actions, each with specific lessons.
In 1983, heavy US casualties at the Marine barracks in Lebanon taught the cost of fixed positions in hostile territory. The use of American forces in Grenada (1983) and Panama (1989) amounted to not much more than the military equivalent of a police SWAT team breaking into a crack house - without a great deal of risk to troops or the likelihood of bogging down into a lengthy stay.
Haiti and Bosnia were another matter: US troops stayed much longer (there still are more than 6,000 US military personnel in Bosnia), and in neither case has the result been a tidy political outcome.
The engagement in Somalia between 1992 and 1994 was a brief but violent foray that is generally seen as a disaster - certainly in terms of public reaction to the loss of 29 American servicemen in combat there.
Attitudes after the cold war
In the post-cold-war era, with the United States the only remaining superpower, Americans apparently are skeptical of wielding the nation's military might.
According to a recent survey by the Chicago Council on Foreign Relations, the only circumstance in which most Americans would favor the use of US ground troops today is a strike against a terrorist training camp. Preventing the spread of nuclear weapons and stopping the flow of illegal drugs into the country are top priorities as well.
But according to this survey, "Among the lowest priorities are helping to improve the standard of living of less developed nations, helping to bring a democratic form of government to other nations, and protecting weaker nations against foreign aggression." Only about one-third of those polled ranked "regional ethnic conflicts" - what has been the story in the Balkans for hundreds of years - among threats to US vital interests.
In the Gulf War, the Bush administration was careful to delineate specific reasons for putting US forces in danger: getting Iraqi invaders out of Kuwait, protecting US oil sources, defending nearby Israel.
In Kosovo, a part of sovereign Yugoslavia, the reasons seem less clear.
Preventing Serb attacks on Albanian Kosovars, especially civilians, is a "moral imperative," according to President Clinton. But the current fighting also has longer-term ramifications directly related to US security, Mr. Clinton asserts.
"Americans have learned the hard way that our home is not that far from Europe," Clinton said in his Saturday radio address. "Through two World Wars and a long cold war, we saw that it was a short step from a small brush fire to an inferno, especially in the tinderbox of the Balkans. The time to put out a fire is before it spreads and burns down the neighborhood."
Some warn that this amounts to an escalation of purpose, for the United States and for the 19-nation Western military alliance formed 50 years in the wake of World War II.
"Never has NATO [threatened] to go into another country that's not threatening neighboring countries, not threatening part of the alliance, to quell a civil war," Senate majority whip Don Nickles (R) of Oklahoma warned before the strikes began. "NATO is a defensive alliance."
Sen. John Warner (R) of Virginia disagreed. "The credibility of NATO is on the line," he said. "The credibility of the United States working with its European partners in NATO is on the line."
"The NATO alliance has great relevancy to the 21st century and the end of the 20th in dealing with what we see as the major threats," asserts Secretary of State Albright. "And in our estimation, the biggest threat that we have now is the threat of chaos and instability."
Many worry about what it will take for NATO, and especially the United States, to declare victory in the Balkans and go home - the so-called exit strategy, or endgame. But some say that in the post-cold-war world, this is increasingly difficult to determine.
"The world has changed so fundamentally that this calculus of what the last step will be is no longer relevant, especially if we try to answer it before the first step is taken," argues Sen. Joseph Biden Jr. (D) of Delaware. "It leads to a policy of paralysis."
A moral imperative?
The question of whether to use US forces in war-torn Kosovo - and especially of risking American lives in the process - is a difficult one, even for those who closely follow such matters. Having listed all the reasons for not getting involved there, experts at the Center for Defense Information (a Washington think tank that is often critical of US military policy) concluded that Clinton was right in this case.
"We feel that the moral imperative is such that if we are to - as a nation - be able to look ourselves in the eye in terms of the values that we espouse for ourselves, let alone everybody else in the world, that there has to be something done to try and stop the scorched-earth tactics of the Yugoslavs in Kosovo," says Daniel Smith, chief of research at CDI and a retired US Army colonel who specialized in military intelligence.
Mr. Summers, the retired Army colonel who wrote what may be the definitive critique of US strategy in Vietnam, puts it this way: "If Vietnam taught us nothing else, it was that we cannot fight a war in cold blood and we cannot fight a war without the support of the American people."
If that's true, and if the recent surveys showing increased public skepticism about fighting foreign wars are accurate, then the search for a proper threshold in use of US military force is not over.