Arm the Kurds against Islamic extremists

Iraqi Kurds need help to oppose the Islamic State, which is overrunning Iraq. But instead of support, the Obama administration is undermining Iraqi Kurdistan's right to self-defense, blocking oil sales and discouraging countries from selling weapons. Washington wrongly believes that Iraqi Kurdistan, well-armed and financially independent, represents a greater risk to Iraq's stability than the Islamic State.

Islamic State forces overran Mosul, Iraq's second largest city, on June 10. Fighters swept south occupying one-third of Iraq's territory and killing thousands of Shiites in Nineveh, Anbar, and Diyala provinces. Abu Bakr Al-Baghdadi, head of the Islamic State, declared a caliphate over territories in Iraq and Syria, with himself as emir.

Read MoreU.S. needs to pay attention to what Iran wants in Iraq

He declared the Islamic State on June 30. Recently, the Islamic State has targeted Christians in Mosul. Christians were ordered to convert to Islam and pay a special tax, or face execution. It razed Jonah's tomb and ancient Assyrian churches.

With their advance stalled on Baghdad, Islamic State forces pivoted to confront the Kurds. They attacked Syrian Kurds in Kobani and Hassaka, as well as Iraqi Kurds in regions along the Syrian border.

Fighters of the Islamic State over the weekend seized Sinjar, a Kurdish stronghold in Nineveh Province on the Syria-Iraq border. Its forces also captured the Mosul Dam. If the Islamic State decides to dynamite the dam, major population centers will be swept away and farmlands destroyed. The Islamic State also seized the Ain Zalah oil field, increasing revenue for its war machine. Its black flag flies in Kurdish towns, as the Islamic State advances on Dohuk.

Read MoreA grand bargain between Turkey and the Kurds

Iraq's Prime Minister Nouri Al-Maliki accused the Kurds of conspiring with the Islamic State to destroy Iraq. These latest events prove Maliki's folly. The Kurds have always compromised to preserve Iraq's sovereignty. They have always opposed foreign fighters seeking Iraq's destruction.

Kurdish Peshmerga forces take security measures against the armed Islamic State-led militants' attacks to regain the control of Celavle town of Diyala from peshmerga forces in Iraq on July 31, 2014.
Feriq Ferec | Anadalou Agency | Getty Images
Kurdish Peshmerga forces take security measures against the armed Islamic State-led militants' attacks to regain the control of Celavle town of Diyala from peshmerga forces in Iraq on July 31, 2014.

The Kurdistan Regional Government (KRG) recently sent a high-level delegation to Washington. Iraqi Kurds do not want to be accused of dividing Iraq. They expressed Iraqi Kurdistan's commitment to political dialogue.

In return for cooperating with the Obama administration, KRG officials insisted on Iraqi Kurdistan's right to self-defense and, as established by Iraq's Federal Court, Iraqi Kurdistan's right to sell oil.

Read MoreUS tightens restrictions for flights over Iraq

However, they were rebuffed. The United States refuses to support Kurdish militia called Peshmerga – "those who stand before death." Peshemerga were outgunned in the weekend battle. Sophisticated weapons provided by the U.S. to Iraq's Armed Forces were seized by the Islamic State, and used against the Kurds.

The Kurds are not looking for a handout. They are prepared to buy weapons in order to defend themselves. Peshmerga are the only force capable of countering and ultimately destroying the Islamic State.

But Instead of helping the peshmerga, the Obama administration is working diplomatic channels to discourage countries from selling weapons to the Kurds. It is also lobbying countries to prevent them from buying oil from Iraqi Kurdistan.

Iraqi Kurdistan opened a pipeline transporting crude to storage facilities in the Turkish port of Ceyhan on May 2. Turkey opened the pipeline over Washington's objection. However, Turkey refuses to buy oil from Iraqi Kurdistan under pressure from Washington.

The Obama administration also intervened with the Moroccan government to block delivery of oil from Iraqi Kurdistan. A tanker recently anchored in international waters off Galveston, Texas. A U.S. district court intervened to block the sale to U.S. refiners. Without a royalty and revenue-sharing deal between Baghdad and the Kurdistan Regional Government, which Maliki blocks, Baghdad is threatening to sue anyone who tries to buy oil from Iraqi Kurdistan.

Read MoreExtremists in Iraq need a history lesson: Phillips

The Islamic State is civilization's enemy. It vows to take over Iraq and Syria, attack Jordan and Israel, slaughtering Shiites, Kurds, and supporters of the West. Iraqi Kurdistan is America's friend, not its foe.

A new reality exists in Iraq. The Obama administration still believes that a government of national unity in Baghdad, backed and controlled by Iran, can deter the Islamic State's advance.

The weekend's events are a wake-up call. Iraqi Kurds are the only effective force to counter the Islamic State.

The Obama administration should train and equip the peshmerga. At the very least, it should allow the peshmerga to buy arms to defend themselves.

It should also facilitate, not obstruct, the sale of oil from Iraqi Kurdistan.

When the Islamic State occupies Amman and joins forces with Hamas to attack Israel, the Obama administration will look back on this moment, wishing it had supported the Kurds to oppose Islamic extremism.

Commentary by David L. Phillips, director of the Program on Peace-building and Human Rights at Columbia University's Institute for the Study of Human Rights. He is a former senior adviser and foreign affairs expert to the U.S. Department of State during the administrations of Presidents Clinton, Bush and Obama. He is also author of the forthcoming book, "The Kurdish Spring: A New Map for the Middle East" (Transaction Publishers).