CLIFFORD D. MAY: The Kurdish test. “Iran’s mullahs are betting that Trump, like Obama, will choose appeasement.”

Now the Kurds are imperiled. Here’s what’s happened: On Oct. 13, President Trump announced his Iran strategy. He declined to recertify the nuclear arms deal concluded by his predecessor. Among the reasons: Iran’s compliance cannot be verified so long as international inspectors are barred from the regime’s military facilities.

The president also is unwilling to turn a blind eye to Iran’s continuing development of missiles designed to deliver nuclear warheads, the “sunset” clauses that legitimize the mullah’s nuclear weapons program over time, and the terrorism that those mullahs sponsor. Notably, he designated Iran’s Islamic Revolutionary Guards Corps (IRGC) as a terrorist organization.

The Iranian response has been more than merely rhetorical. On Oct. 16, Iraqi forces, over which Iran’s rulers now exercise considerable influence, and Shia militias, many of them Iranian-backed, drove Kurdish troops out of oil-rich Kirkuk. According to credible reports, Maj. Gen. Qassem Soleimani, the commander of foreign operations for the IRGC, was on hand to personally coordinate the operation.

Though Kirkuk is beyond the de facto borders of the KRG, Kurds have long viewed it as the Jerusalem of their homeland. It was a Kurdish-majority city until the Saddam regime determined to “Arabize” it, not least through population transfers.

In 2014, however, when the Islamic State was on the march, Iraqi government forces abandoned Kirkuk. The Peshmerga quickly filled the vacuum, defending the city and holding it ever since.

By orchestrating the taking of Kirkuk, Iran’s rulers are testing Mr. Trump. They are betting that, despite the tough talk, he won’t have the stomach to do what is necessary to frustrate their neo-imperialist ambitions.

Lending full material support to the Kurds is the best and fastest way to check Iran’s territorial ambitions.