The birth of Macedonia in 1991 - the only former Yugoslav republic to gain its independence without bloodshed - gave rise to one of the longest diplomatic disputes in the region.
By Gabriel Partos
BBC South-East Europe analyst
From the very beginning, Greece has been objecting to various aspects of independent Macedonia's state symbols and laws.
As a result, Macedonia has amended its constitution and changed its flag - and in the process brought to an end a damaging Greek trade embargo in 1995.
Macedonia had to change its flag to avoid Greece's wrath
But one issue has remained unresolved. Greece believes that the very name Macedonia implies a territorial claim to its own northern province of the same name.
And as a consequence of Greek opposition to recognition of Macedonia by its own constitutional name as the Republic of Macedonia, when the representatives of the Skopje government took their seats at the United Nations after some delay in 1993, they sat behind a name plate referring to the former Yugoslav republic of Macedonia, or Fyrom for short.
That provisional arrangement has remained in force ever since at the UN and other international organisations - much to Macedonia's irritation.
But in their bilateral dealings with Macedonia a number of countries, including Russia, China and even Turkey, a Nato member, have been using Macedonia's own preferred name over the years.
In general, though, Greece's Nato allies and, of course, fellow European Union members have been complying with Greece's wishes on this issue.
Now Washington has broken ranks by reportedly deciding to grant formal recognition to Macedonia by its own constitutional name, a development that has angered Greece.
For now, the EU countries are unlikely to follow suit, given that Greece would almost certainly oppose it tooth and nail.
"We heard the position of the United States, we will look through the implications of it," said Dutch Prime Minister Jan-Peter Balkenende, whose country holds the EU presidency.
"As you know, the European Union at this moment has the position that the official name is the former Yugoslavian republic of Macedonia and I think for the time being we can use this name, but we will look to the consequences."
Washington's move has not been entirely unexpected.
Last year, among the many treaties the US concluded with other states to exempt US citizens from the jurisdiction of the International Criminal Court, its agreement with Macedonia referred to the "government of Macedonia".
That caused a stir in Athens, which Washington then sought to calm down by saying the accord had been an informal one.
But since then other agreements followed - including one on military co-operation which was signed when US Defence Secretary Donald Rumsfeld visited Macedonia last month.
During his visit, Mr Rumsfeld also praised Macedonia which has been supporting the US stand on Iraq, and has contributed a small contingent of 30 troops to the coalition forces based there.
By contrast, Greece has stayed away from Iraq. And there is a strong strand of anti-Americanism in Greece which led to the cancellation of Secretary of State's Colin Powell's planned visit to Athens at the time of the Olympics.