President Biden is recognizing the massacre of Armenians by the Ottoman Empire as a genocide, a significant move that risks angering Turkey. Previous presidents have marked April 24, which is Armenian Genocide Remembrance Day, but have not used the term “genocide” to refer to the mass killings that occurred between 1915 and 1923. 

“Each year on this day, we remember the lives of all those who died in the Ottoman-era Armenian genocide and recommit ourselves to preventing such an atrocity from ever again occurring,” Mr. Biden said in a statement on Saturday. “We honor their story. We see that pain. We affirm the history. We do this not to cast blame but to ensure that what happened is never repeated.”

The declaration came after Mr. Biden spoke with Turkish President Tayyip Erdogan on Friday, although statements from both governments after the call made no mention of the plan. The White House said Mr. Biden conveyed to Erdogan “his interest in a constructive bilateral relationship with expanded areas of cooperation and effective management of disagreements.” The two also agreed to hold a bilateral meeting at the NATO summit this June.

The readout of the call by the Turkish government said the two leaders “agreed on the importance of working together to expand cooperation based on the strategic nature of bilateral relations and mutual interests.”

Until now, no U.S. president has formally recognized the killings as genocide, wary of worsening ties with Turkey, a NATO ally. As a presidential candidate, Mr. Biden pledged to declare it as genocide.

“I pledge to support a resolution recognizing the Armenian Genocide and will make universal human rights a top priority for my administration,” Mr. Biden said in a statement marking Armenian Genocide Remembrance Day last year.

In a 2020 interview with The New York Times editorial board, Mr. Biden said he had “spent a lot of time” with Erdogan and called him an “autocrat.” In 2014, Mr. Biden — then the vice president — offered an official apology to Erdogan for suggesting that Turkey played a role in the rise of ISIS.

Former President Trump often spoke highly of Erdogan, despite the leader’s troubling human rights record. In 2019, Mr. Trump urged Republican senators to block a resolution recognizing the killings as “genocide.” GOP Senator Lindsey Graham did so in November of that year, but later said it was because Erdogan was visiting Washington at the time. The bill was blocked again by Republican Senator David Perdue, but then passed overwhelmingly in both houses of Congress in December 2019. However, the Trump State Department said in a statement at the time that the resolution did not reflect administration policy.

In a statement, Speaker Nancy Pelosi praised Mr. Biden for using the term “genocide.”

“On April 24, and every day, we remember the victims and survivors who endured nearly incomprehensible suffering and pledge to honor their lives by recognizing this brutality for what it was: genocide. But tragically, the truth of these heinous crimes has too often been denied, its monstrosity minimized,” Pelosi said. “That is why our hearts are full of joy that President Biden has taken the historic step of joining Congress with formal recognition on Armenian Genocide Day.”

Former President Obama had also avoided using the term “genocide” when marking the April 24 day of remembrance, despite pledging as a candidate to recognize it as such.

The genocide entailed the ethnic cleansing and mass murder of over 1 million ethnic Armenians by the Ottoman Empire and Committee of Union and Progress during World War I. Turkey has repeatedly denied that what happened was wrongful or genocide, arguing that there were losses on both sides, and has estimated the death toll at around 300,000 Armenians.