Senate Democrats wrote a letter to the Library of Congress on Wednesday demanding the national institution refer to the 20th century killings of Armenians in Turkey as a “genocide.” The move comes at a time of friction between some members of Congress and the Trump administration on Turkey, and as Turkey has backed Azerbaijani forces against Armenian ones in the breakaway region of Nagorno-Karabakh.

Robert Menendez of New Jersey, who is the highest-ranking Democrat on the Senate Foreign Relations Committee, signed the letter along with fellow Democratic Sens. Chuck Schumer of New York, Sheldon Whitehouse of Rhode Island and Elizabeth Warren of Massachusetts.

The term Armenian genocide is often used to refer to the killings and forced displacement of Armenians from 1915-23 by Turks; Greeks and Assyrians were also killed. The Turkish government admits there were deaths, but adamantly disputes the events constituted a genocide.

The Library of Congress currently refers to the period as the “Armenian massacre” in its database. The senators wrote the letter in support of recent efforts by the University of California, Los Angeles and the Armenian National Committee of America to change this phrasing.