By Laura Smith-Spark
BBC News, Washington
Despite a direct appeal by US President George W Bush, lawmakers in the US have backed a description of the mass killings of Armenians by Ottoman Turks after 1915 as genocide.
The issue of what happened to the Armenians remains hugely divisive
The resolution, passed by the House of Representatives' Foreign Affairs committee, was written by Democrat Adam Schiff, whose California district is home to the US's largest ethnic-Armenian community.
Across the country, Armenian-Americans have been lobbying politicians, and publicising their view of the massacres as genocide - a suggestion the Turkish government and most Turks furiously reject.
Historians are also divided on whether this was a case of genocide. More than 20 countries have formally recognised genocide against the Armenians, however.
Given that Armenians represent only about 1.5m of America's 300m population, what has won them such influence over the US Congress - and perhaps the nation's foreign policy?
Part of the answer lies in the organisation and determination of the Armenian-American lobby groups, says Dr Svante Cornell, of the Central Asia-Caucasus Institute at Johns Hopkins University.
The Armenian National Committee of America (ANCA) and the Armenian Assembly of America (AAA) are among the most powerful.
Another factor is that the Armenian-American community is largely concentrated in important states such as California, Michigan and Massachusetts, Dr Cornell said.
"You have basically a number of places where the Armenian issue is very important in local politics - especially for anybody wanting to get elected in California," he said.
"The Turkish lobby is much less organised and much less rooted in an electorate than the Armenian lobby."
Of course, the vote - with 27 for and 21 against - was also based on representatives' competing sets of principles.
Opening the debate, Tom Lantos, the committee's Democratic chairman, acknowledged that the resolution posed a "sobering" choice.
"We have to weigh the desire to express our solidarity with the Armenian people... against the risk that it could cause young men and women in the uniform of the United States armed services to pay an even heavier price than they are currently paying," he said.
Divisions within the committee ultimately crossed party lines, with eight Democrats voting against the measure (19 backed it) and eight Republicans voting for it (13 opposed it).
Opponents of the resolution argue it could endanger US national security and that now is not the time to have the debate.
Supporters draw a parallel between the mass killing of Armenians and what is happening in the Darfur region of Sudan today - and say the US must speak now if it is to maintain credibility on human rights.
Dr Rouben Adalian, of the Armenian National Institute in Washington, told the BBC's World Today: "In a world where genocide continues to occur, there is something to be said about acknowledging past genocides as a way of preventing others."
For Bryan Ardouny, executive director of the AAA, the passage of the resolution "was a historic step forward" in ending what he calls the "denial campaign" of the Turkish government.
"We very much appreciate the support of the whole Armenian community around the country but also the members of Congress who stood their ground and voted yes for the resolution," he said.
The AAA has worked very closely with the sponsors and co-sponsors of the resolution, he said, as well as talking to members of Congress from both parties about the issue.
The close-knit Armenian-American diaspora has also been at work educating other communities and writing to politicians, Mr Ardouny said.
"The response has been great in terms of activism throughout the entire Armenian-American community," he said.
"One of the consequences of the genocide was that Armenians came to the US. My grandparents were genocide survivors - they came to this country, they got an education, they became part of the American fabric.
"We have a very vibrant, passionate, educated constituency that feels very strongly and passionately about this and the fact it's still being denied - this is something that's painful."
Some people argue that it is not the place of legislators to decide history - especially on an issue as fiercely contested as this one.
Turkish President Abdullah Gul called the US vote unacceptable
A decision by Turkey to recall its ambassador for consultations may be just the first in a series of steps as it considers future US-Turkish relations.
Turkish President Abdullah Gul criticised some US politicians as having "sought to sacrifice big problems for small domestic political games" in pursuing the resolution's passage.
Dr Cornell saw it as a "strategic reality that this will deal a very heavy blow to US policy in the Middle East and with regard to Iraq".
The US has already lost much support among the Turkish people in recent years, he said.
The resolution is expected to come to the full House before the session adjourns on 16 November.
Back in 2000, a similar resolution failed when it was withdrawn from the floor of the then Republican-controlled House at the urging of then President Bill Clinton, who said it could put at risk American lives and further inflame tensions in the Middle East.
Seven years later, it remains to be seen whether the Democratic-controlled House will heed the warnings of Mr Bush.