BOSTON (JTA) — The massacre of 1.5 million Armenians in the early years of the 20^th century was “unequivocally genocide,” the head of the Anti-Defamation League said.

His added that his organization will support U.S. recognition of the Armenian Genocide, a move the civil rights group resisted for many years.

ADL CEO Jonathan Greenblatt on Friday staked out the ADL’s strongest position on the subject in his blog post for Yom Hashoah, Holocaust Remembrance Day in Israel, ahead of the organization’s national convention that began Sunday in Washington, D.C. Greenblatt tied the events to the Holocaust.

“Let me be crystal clear: …What happened in the Ottoman Empire to the Armenians beginning in 1915 was genocide,” he wrote.

“We believe that remembering and educating people about any genocide – Armenian, the Holocaust, Bosnia, Rwanda and others is a necessary tool to prevent future tragedies,” he also wrote.

Greenblatt said that the Jewish community’s experience regarding the Holocaust is relevant to the discussion, pointing out that at the end of World War II, there was “wide­spread shame in the West­ern world at the real­iza­tion that anti-Semitism was deeply embed­ded across cul­tures and coun­tries and could pro­duce such hor­ror.”

He cautioned that the passage of time since the Holocaust has in some way eviscerated the sense of shame that has inhibited anti-Semitism, and is allowing it to reemerge in full force, which shows that “we must edu­cate each gen­er­a­tion about the tragedies of the past.”

“Silence is not an option,” he wrote.

Until August, 2007, the ADL, under the leadership of then-National Director Abraham Foxman, did not use the term genocide to describe the massacre. It reversed course after an internal debate went public and a grassroots campaign by Armenian American activists targeted the ADL in Boston and other cities and towns with large Armenian populations.

Foxman has since used the term Armenian genocide including in a 2014 speech. For many years, the group opposed formal recognition by the U.S. Congress, citing concerns for the Turkish Jewish community and relationship between Turkey, Israel and the U.S.

New England’s ADL Director Robert Trestan told the Boston Globe on Sunday that Greenblatt’s post was the “most unequivocal statement that we’ve ever issued.” Trestan took part in meetings between the ADL and local and national Armenian and Jewish groups, the Globe reported.

The statement does not go far enough, according to Andrew Tarsy, the former New England ADL director whose dispute over the issue with the national leadership in 2007 led to his temporary ouster by Foxman, who later reinstated Tarsy.

Tarsy, a noted civil rights attorney, told the Globe that the ADL ought to lead conversations about reparations for families. “Everything that Holocaust reparations has represented should be on the table,” he said.