US President Barack Obama has marked the 95th anniversary of the massacre of Armenians by Turkish forces in World War I, calling it one of the worst atrocities of the 20th century.
In a statement issued by the White House, Mr Obama said 1.5 million Armenians were massacred or marched to their death in the final days of the Ottoman Empire.
The president said the 1915 massacre must not be repeated, but did not refer to a debate over whether Turkey was responsible.
Turkey withdrew its ambassador to Washington in March after a House of Representatives committee voted on a nonbinding "genocide" resolution over the killings.
A deal between Turkey and Armenia to establish diplomatic ties and reopen their border collapsed on Thursday.