US President Joe Biden's remarks on the events of 1915 are "unacceptable" and a "historical mistake," Azerbaijan's President Ilham Aliyev said on Saturday.
Aliyev and Turkey's President Recep Tayyip Erdoğan condemned Biden's move during a phone call, the Azerbaijani Presidency said in a statement.
The Azerbaijani leader said the US president's remarks would "seriously damage cooperation in the region," stressing that Baku will always stand by Ankara.
Aliyev's statement came shortly after Biden called the events of 1915 an "Armenian genocide," breaking American presidents' long-held tradition of refraining from using the term.
Turkish authorities and leaders strongly rejected the assertion, with the Foreign Ministry saying that Biden's statement lacks any scholarly or legal basis and is not supported by evidence.
Fahrettin Altun, Turkey's communications director, said that US officials ignored history to bow down to the demands of lobbyists.
Turkey's position on the events of 1915 is that the deaths of Armenians in eastern Anatolia took place when some sided with invading Russians and revolted against Ottoman forces. A subsequent relocation of Armenians resulted in numerous casualties.
Turkey objects to the presentation of these incidents as "genocide," describing them as a tragedy in which both sides suffered casualties.
Ankara has repeatedly proposed the creation of a joint commission of historians from Turkey and Armenia as well as international experts to tackle the issue.
In 2014, then-Prime Minister Erdoğan expressed condolences to the descendants of Armenians who lost their lives in the events of 1915.
