“President Barzani was obligated to conduct the referendum and now is obligated to respond to that result,” Mr. Ali said. “We’ve repeatedly said we can negotiate but that has to be on the question of independence.”
Kurdish officials have expressed dismay at the lack of support they have found internationally, with the United States and other powers, as well as the United Nations, critical of the decision to even hold the referendum, and none expressing approval for the pro-independence result.
Hoshyar Zebari, who helped lead the referendum drive in the Kurdish region and was formerly Iraq’s foreign minister, said that criticism of the vote from the United States had “emboldened Baghdad” to take a hard-line position toward the Kurds. Baghdad’s threatened retaliation was, he said, “very damaging and provocative, and illogical and destructive.”
Mr. Ali said the Kurds were hopeful that international allies would eventually come around to the idea of Kurdish independence, and said they were heartened at some individual voices praising the referendum result. He cited, for instance, Charles E. Schumer of New York, the minority leader in the United States Senate, , who on Wednesday praised the Kurdish independence vote.
Iraq’s influential Shia spiritual leader, Ayatollah Ali al Sistani, in his Friday sermon in the southern city of Karbala, was strongly critical of the Kurdish move. “Any individual steps toward division and separation and the attempt of making this thing reality will lead to internal and external reaction and bad consequences that would damage our dear Kurdish citizens in the first place and maybe lead to what is more dangerous than that, God forbid, and will give way for many regional and international sides to intervene in Iraqi affairs,” Ayatollah Sistani said.
On Friday, military officials in Baghdad confirmed that the strategic highway linking Mosul and the northern city of Dohuk, in Kurdish-held territory, was closed by the Iraqi military for several hours. In addition, protests by civilians forced the closure of the Kirkuk-Baghdad highway on Friday. Saad al-Hadithi, the spokesman for Prime Minister Haider al-Abadi of Iraq, said that land borders would also be closed between Iraq’s Kurdish region and Turkey and Iran, but there was no confirmation if that had actually happened.
The Iraq border agency announced that it was sending convoys of police officers and Interior Ministry officials to guard three key land border crossings between the Kurdish region and Syria, Turkey and Iran beginning on Saturday.
Mr. Ali said that he was aware of no such move and that it would be unconstitutional.
He said that cutting off the Kurdish region’s trade with Turkey, which he said totals $17 billion a year, would hurt everyone.
He also warned of measures that the Kurdish regional government could take if Iraq’s crackdown on air travel and the borders continued, including severing internet and mobile telephone coverage, much of it based in the region, and even the supply of cement, most of which comes from the region.
“The list is very long. There’s a lot we can do, if we’re talking about that,” he said. “We could cut off communications. We can also close the Erbil International Airport to domestic flights, to Baghdad and Najaf.” That, he said, would hurt many Iraqi officials whose family members live in the Kurdish region. “The families of all their policy makers live in Erbil because it’s not safe in Baghdad anymore,” Mr. Ali said.
Mr. Ali also scoffed at Iraqi threats to move troops into Kirkuk, the oil-rich city claimed by both Arabs and Kurds. Kurdish forces took control of most of the city after Islamic State extremists chased the Iraqi army out in 2014.
“They’re talking about sending troops?,” Mr. Ali asked. “They couldn’t enter Kirkuk under ISIS, they couldn’t liberate it then, and now?”
Flights after 5 p.m. on Friday were canceled by international airlines flying out of Erbil, according to travelers at the airport, with the Iraqi ban due to go into effect at 6 p.m.
Prime Minister Abadi’s office released a statement that the Kurdish region’s two international airports, in Erbil and Suleimaniya, could be reopened as soon as Kurdish officials transferred control of them to the federal government. Kurdish officials said that was not going to happen.