ERBIL — Defying pressure from the United States and regional powers Turkey and Iran, millions of Kurds cast their ballots today in a historic referendum on long-fought Kurdish independence.

Massoud Barzani, president of Iraqi Kurdistan, who is leading the independence drive, exuded confidence after voting at a polling station close to the presidential compound overlooking Erbil, where the Kurdistan Regional Government (KRG) sits. As election observers looked on, his eldest son, Masrour, chancellor of the Kurdistan Region Security Council, was up next, dipping his index finger in the indelible indigo ink meant to prevent repeat balloting.

At a polling station in Salahuddin, the mood was festive, with citizens taking selfies while lined up outside classrooms where ballots were being cast. “I am so happy,” said Shermin, a 20-year-old student who had come with her family to vote. “I want independence, right now.”

The jubilation expressed by the red, green and yellow Kurdish tricolor festooning streets, homes, cars and shopping malls was tinged with trepidation amid angry threats, thus far largely hollow, from Turkey and Iran. Both countries, which are home to large and restive Kurdish populations, have voiced stiff opposition to the referendum. Turkey deployed tanks along its border with the de facto Kurdish state, where Turkish units carried out drills. Turkish Prime Minister Binali Yildirim said Ankara views the results of the referendum as “null and void.” On Saturday, the Turkish parliament extended the mandate for Turkish troops stationed in Iraq and Syria by a year.