Nearly nine weeks into its air war against Yugoslavia, NATO is staring a protracted conflict in the face - causing some alliance members to become restive.
The longer the air campaign goes on, the greater the military, economic, and political costs. Those increase significantly if NATO moves to a ground war.
The hope is that patience and the air campaign will win the day, and Yugoslav President Slobodan Milosevic will back down. But if he doesn't, everything from NATO unity to US credibility could be at stake.
"At the most basic level, once one starts to fight a war, part of the risk is it can go in many areas that you just can't foresee," says Robert Zoellick, an undersecretary of State in the Bush administration.
President Clinton has appealed to the American public to remain steadfast behind the effort to reverse Mr. Milosevic's "ethnic cleansing" of Kosovo, saying the US must be ready "to pay the price of time."
At this moment, the economic costs to the US appear to be manageable. Congress is expected to hand the president $12 billion in emergency spending for military and humanitarian assistance through September, though some believe the humanitarian portion will fall short.
Cynthia Latta, principal economist at Standard & Poor's DRI, says an air-only campaign "could go on indefinitely" without serious repercussions to the nation's economy, though a ground war could spark higher interest rates.
But ominously for President Clinton and his NATO allies, while the dollars are there, public opinion is starting to crack. According to a new poll by the Pew Research Center here, approval of US participation in the war has dropped from 62 percent in mid-April to 53 percent.
The less the support and the longer the military stalemate, the more difficult it will be for NATO to stay a common course.
The pressures of domestic public opinion are now causing at least rhetorical dissension among alliance members. That dissension burst into the open this week, when German Chancellor Gerhard Schrder bluntly rejected Britain's position that the allies should pre-position troops for a possible Kosovo invasion.
"While the European publics have been relatively stalwart, if they perceive that bombing is going on for a very long period of time without achieving the objectives, they'll start to flake off," says Mr. Zoellick.
Again, ground war could alter public opinion. Polls show the share of Americans opposed to ground troops increasing.
Zoellick believes NATO should at least pre-position troops. But what particularly disturbs him is the possibility that, faced with a long air campaign that is neither winning nor losing, NATO will settle for some "messy compromise" that undermines the credibility of the United States.
"Whatever one thinks of the aftermath of the Persian Gulf War, it did leave a residue of serious respect for United States military capabilities.... That premium is going to be lost," he says.
John Hillen, a senior fellow at the Center for Strategic and International Studies in Washington, worries about the US military being spread too thin.
"You can carry on [in Yugoslavia] for quite some time, but this decreases our flexibility and increases the danger in other areas of the world," he says.
A security expert close to the administration is less alarmist. "There may be shortages and military-readiness issues, but I don't think so far they've risen to the level of a real nightmare."
This expert agrees with others, however, that one of the greatest risks in a longer war is the unknown consequences, especially after unexpected events such as the bombing of the Chinese Embassy in Belgrade.