IRBIL, Iraq — Blue and white Israeli flags have become a common sight in the Kurdish regional capital, Irbil. Some Kurds fly them on their cars. Others waved them enthusiastically at massive rallies ahead of Monday’s referendum on independence.

Israel has been a vocal advocate of Kurdish independence in the lead-up to the vote, and in a region where Israeli flags are most often seen being trampled or burned, the images were striking. They have provided easy fodder for the referendum’s opponents, who point to an Israeli plot to break up Iraq.

The old Kurdish adage — that Kurds have “no friends but the mountains” — had looked to be somewhat apt ahead of the referendum, as even longtime allies of Iraqi Kurdistan came out in opposition. Turkey, Iran and Iraq have mulled retaliatory measures. The United States has urged a postponement, which some Kurds have criticized as a betrayal.

Israel, though, had expressed wholehearted support - until recently at least. Historically Israel has had cordial ties with the Kurds, in a generally hostile region, its politicians say they feel a natural kinship with the Kurds, seeing similarities in their struggle for a homeland, against the odds.

The referendum though, has shone a new spotlight on the relationship, and at least some Kurds appear to be sensitive to that sentiment.

Last week, a man entering a referendum rally in Irbil's main park was stopped by police who confiscated an Israeli flag he carried. The police officer folded the flag neatly and placed it on the back seat of his vehicle.

After tweeting his support earlier this month, Prime Minster Benjamin Netanyahu has now instructed his ministers to avoid publicly commenting on the referendum, according to one government official, who declined to elaborate or be named due to the sensitivity of the subject.

On the eve of the referendum, Barzani dismissed talk of the vote creating a “second Israel,” calling it “ridiculous.” That followed a warning from Iraq’s former prime minister, Nouri al-Maliki, who said the Kurdish region could become an Israeli satellite state in northern Iraq.

“We will not take any Israeli intervention in the region with our arms folded,” Iraqi Shiite cleric Moqtada al-Sadr said in a statement.

Turkish newspapers, meanwhile, have been filled with conspiracy theories alleging that Barzani has agreed to repatriate hundreds of thousands of Jews to the region.

The Israeli relationship with the Kurds has deep roots. Kurdistan’s Jews trace their heritage to the members of the Israelite tribe of Benjamin, who arrived in the area in the 8th century B.C. Today, there are more than 200,000 Kurdish Jews in Israel.

Following what was known in Iraq as the “Farhud” — violence and looting targeting the country’s Jewish population — the Kurds played a pivotal role in helping Jews escape in the decades that followed. Jewish families have recounted how Masoud Barzani, now president of the Kurdistan regional government, personally helped smuggle them out over the mountains.

Israel also provided military support to the Kurds, including trainers, antiaircraft weaponry and a military hospital, according to the Mossad intelligency agency's station chief in Irbil in the 1970s.

For Israel, support of Kurdistan is consistent with a long-standing foreign policy strategy. Since the time of Israel’s first prime minister, David Ben-Gurion, the country has pursued what it calls the “periphery doctrine.” Isolated in a region of enemies following its independence in 1948, Israel attempted to form alliances with non-Arab and minority populations in the Middle East.

Initially that included Iran, but following its 1979 Islamic revolution, Tehran severed ties with Israel. Now, it’s Iran that Israel wants to counter.

“While the Arab nation-states are eroding, we must find our allies, our sustainable allies,” said Gideon Saar, a former Israeli interior minister who has urged Prime Minister Benjamin Netanyahu to do more to lobby for the Kurdish cause in his meetings with President Trump.

“You can see how much Iran is investing in having hostile forces on our borders, so having friends for Israel in the region is extremely important,” said Saar, who met with a Barzani adviser when the Kurdish leader visited Israel earlier this year and disclosed the intention to hold a referendum on independence.

Israel has also maintained economic ties with Kurdistan, purchasing Kurdish oil despite objections from Iraq’s central government in Baghdad.

On the eve of the vote, a small but rowdy group of Jewish Kurds gathered in Jerusalem to show solidarity with Kurdistan, holding hands and dancing to the beat of a drum.

“We want to tell the world that the Kurds in Israel support the Kurds in Kurdistan who want to create an independent country,” said Herzl Levy, head of the association of Kurdish Jews in Israel. He said that unlike emigres from other countries, Kurdish Jews kept warm relations with their brethren at home when they left.

“We want to repay them for that,” he said.

But like Israelis, the Kurds are looking regionally isolated as they go to the polls. Iraq
and Turkey have hinted at military action. Turkey has threatened to cut Kurdistan's oil pipeline. Turkey and Iran have separately held military exercises on their borders with the Kurdish region. And Iran has stopped flights.

Morris reported from Jerusalem. Mustafa Salim in Irbil and Ruth Eglash in Jerusalem contributed to this report.