US President Barack Obama said Thursday that the "full, frank and just acknowledgement" of facts surrounding the World War I mass killings of Armenians in the Ottoman Empire was in everyone`s interest.
In a statement marking the 99th anniversary of the start of the killings and deportations, Obama said the United States grieved for the lives lost.
"A full, frank, and just acknowledgement of the facts is in all of our interests," Obama said.
"Peoples and nations grow stronger, and build a foundation for a more just and tolerant future, by acknowledging and reckoning with painful elements of the past."
He added: "We continue to learn this lesson in the United States, as we strive to reconcile some of the darkest moments in our own history."
"We recognize and commend the growing number of courageous Armenians and Turks who have already taken this path, and encourage more to do so, with the backing of their governments, and mine," Obama said in the statement that made no mention of the term "genocide."
In an unprecedented move described by Washington as a historic gesture, Turkish Prime Minister Recep Tayyip Erdogan on Wednesday offered condolences over the massacres, calling them "our shared pain."
Armenians say up to 1.5 million people were killed during World War I, as the Ottoman Empire was falling apart, a claim supported by several other countries.
Turkey meanwhile argues 300,000 to 500,000 Armenians and at least as many Turks died in civil strife when Armenians rose up against their Ottoman rulers siding with invading Russian troops.
Thursday was a day of national mourning in Armenia and requiem masses were held in churches across the country.
So far, over 20 countries have recognized the massacres as genocide.
Obama issued his statement while on a week-long tour of Asia.