To justify the war in Kosovo, the United States cites human rights, self-determination, and other modern ideals.
To bolster their side, the Serbs point to a 14th-century prince named Lazar and a 20th-century dictator named Hitler.
At heart, this war may be a battle between American ideals and Serbia's sense of its ethnic past.
History is helping the Serbs rationalize an almost impossible fight against NATO, the strongest military alliance in the world created 50 years ago this week to protect democracies in Europe.
State television here airs footage of the German Luftwaffe blanketing Belgrade with bombs on April 6, 1941. The attack by Hitler's troops killed from 5,000 to 20,000 Serbs who were opposed to the Axis powers.
"Politics is politics," says an analyst in Belgrade. "The memories of the brutal German bombing are real, and it's best for [the government] to capitalize on emotions that already exist."
Serbian leaders refer to NATO soldiers as "genocidal killers." Swastikas can be seen on abandoned Western embassies throughout the city. And almost every NATO-country leader has been likened to Adolf Hitler.
"Between Hitler and Clinton, there is no principal difference," ultranationalist Serb leader Vojislav Seselj said yesterday.
But historical images amid today's crisis run far deeper than World War II, when Hitler's forces bombed and then occupied Yugoslavia for some three years. And those emotions run especially high with regard to Kosovo, the southern province that is considered the birthplace of the Serbian Christian Orthodox Church. Ethnic Albanians are trying to wrest it away, but the Serbs say they will never surrender Kosovo.
The image of the 1389 Battle of Kosovo Polje has become a standard symbol of Serbia's willingness to fight to the death, even if it's in a losing cause.
In that battle, and a in a series of others afterward, the Ottoman Turks defeated and ruled the Serbs, who were led by Prince Lazar, the self-proclaimed "ruler of all Serbs."
At anti-NATO demonstrations throughout Serbia, protesters raise reproductions of a famous painting called "Kosovo Girl," in which a Serbian soldier reclines on a dead Turk, while a young girl quenches his thirst.
Milosevic and 'Field of Blackbirds'
It even appears that Yugoslav President Slobodan Milosevic, who rose to power by exploiting Serbian nationalism in Kosovo 10 years ago, wants to style himself as the next Prince Lazar. According to Serbian folklore, Lazar told his soldiers before the battle of Kosovo Polje - Field of Blackbirds - that "It is better to die in battle than to live in shame."
Under that theory, Milosevic may know he will lose Kosovo in the end. But, by doing so in a heroic way, his people will want him to remain their leader.
Such a willingness of Serbs to absorb a military pounding may be something NATO planners did not take into account when they decided to launch airstrikes against Yugoslavia.
Here in Belgrade, it seems that the deeper NATO strikes, the greater the resistance. That goes for Mr. Milosevic as well, who has shown no signs that he will agree to a peace plan that would effectively make Kosovo an international protectorate, with ethnic Albanian autonomy.
The Yugoslav Army, according to government sources, is well dug in and prepared for a ground war.
NATO has so far claimed it won't send ground trips, but it appears to be slowly moving in that direction. Yesterday, some 6,000 troops were deployed to Albania, on Kosovo's southern border, to aide the refugees.
One official recently claimed that Serbia has some "10,000 volunteers lined up to fight in Kosovo."
More refugees in Yugoslavia
History also may be playing a key role in the collective conscience of the Serbs, who are accused of trying to "ethnically cleanse" Kosovo of its 90 percent ethnic Albanian population. Most Serbs are unmoved by television footage of thousands of ethnic Albanians fleeing Kosovo - partly because they've already seen similar mass exoduses this decade. In addition to the more than one million Croats and Bosnians displaced because of the wars in Bosnia and Croatia this decade, over a half million ethnic Serbs, too, became refugees.
But perhaps no single event evokes more emotion in the minds of Belgrade Serbs than the April 6, 1941, Luftwaffe bombing, in which the downtown zoo, library, museum, and theater were hit, as were residential buildings.
And there is at least one similarity between the German and NATO strikes on Serbia. The Germans targeted a central bridge in Novi Sad. The bridge was eventually rebuilt, only to be destroyed a second time last week by NATO.
Milosevic has already ordered repairs to this bridge and other infrastructure destroyed by NATO bombs.
But, says a retired Yugoslav general here, there are substantial differences between the two attacks, some 58 years apart.
"I was 14 at the time, but I remember the horror of April 6," says Gen. Stevan Mirkovic.
"The first thing that [the German Luftwaffe] hit was a hospital near my house, and then they hit the shelter I was in. We were surprised, frightened, and disorganized. Now the situation is different. The [Yugoslav Army] knew that NATO would attack, and they were ready."