Who's blocking S.1691?

According to a Secrecy News newsletter:

A proposal to investigate the conduct of the United States government towards foreign minorities detained or otherwise placed in jeopardy during World War II is being blocked in the United States Senate by an anonymous "hold," complained Sen. Dianne Feinstein, a sponsor of the measure.

"Unfortunately, someone on the other [i.e. Republican] side of the aisle has placed a hold on the bill. This anonymous person or persons are unwilling to identify themselves or to explain the reasons for the hold."

While I commend Congress and our Nation for finally recognizing and apologizing for the mistreatment of Japanese Americans during World War II, our work in this area is not done. We should also acknowledge the mistreatment experienced by many German Americans, Italian Americans, and European Latin Americans, as well as Jewish refugees.

Most Americans are probably unaware that during World War II, the U.S. Government designated more than 600,000 Italian-born and 300,000 German-born U.S. resident aliens and their families as "enemy aliens."

Approximately 11,000 ethnic Germans, 3,200 ethnic Italians, and scores of Bulgarians, Hungarians, Romanians or other European Americans living in America were taken from their homes and placed in internment camps. Some even remained interned for up to 3 years after the war ended. Unknown numbers of German Americans, Italian Americans, and other Europeans Americans had their property confiscated or their travel restricted, or lived under curfews.

S. 1691 would not grant reparations to victims. It would simply create a commission to review the facts and circumstances of the U.S. Government's treatment of German Americans, Italian Americans and other European Americans during World War II.

  source

Over there, they're "concentration camps". Over here, they're "internment camps".