Turkish President Recep Tayyip Erdogan warned that lawmakers in his country may recognize the deaths of Native Americans as a genocide after Congress rebuffed Turkey and voted to acknowledge and condemn the Armenian genocide.

The proposed move, which would be largely symbolic, came after the Senate unanimously passed a bill recognizing the Turkish genocide of more than a million Armenians in the early 20th century.

Erdogan threatened the tit-for-tat while speaking on a pro-government news channel on Monday, according to the Independent.

“We should oppose [the United States] by reciprocating such decisions in parliament. And that is what we will do,” Erdogan said. “Can we speak about America without mentioning [Native Americans]?

“It is a shameful moment in U.S. history,” he added.

Before passing in the Senate, the bipartisan legislation condemning the Armenian genocide was approved in the House by a 405-11 vote. The vote is a direct rebuke to Turkey, which has lobbied against referring to the slayings as a genocide. Between 1915 and 1923, an estimated 1.5 million Armenians died at the hands of the Ottoman Empire.

Last week’s vote came after three Republicans had previously voted to block the legislation in the Senate at the urging of the White House, which worried the move would damage an already strained relationship with the NATO ally.

Historians estimate that millions of Native Americans died during the European conquest of North and South America. Most of those deaths are believed to have been caused by diseases brought over from Europe.