When President Biden became the first U.S. president to recognize the Armenian genocide, the massacres and deportations that took place in the Ottoman Empire in 1915 were suddenly back in the news. Past U.S. leaders refused to recognize the genocide to avoid angering Turkey, but times have changed. The relationship between the two NATO allies has turned icy. What happened in 1915 -- and why it matters -- with Middle East historian Howard Eissenstat.