to defeat the jihadist forces. If President Obama wants to break the Islamic State in Iraq and give that country a chance to survive, he needs to help organize and equip a true Kurdish army, The NewYork Times said.

Until now, Mr. Obama has refused substantial aid to the Kurds because of the State Department’s “One Iraq” policy. Washington fears that a strong Kurdistan could end up fighting the Iraqi Army for disputed territory or declaring independence, upending United States policy and pitting Turkey against the new state.

In the meantime, the Islamic State has made the “One Iraq” policy obsolete. The jihadists now control close to a third of Iraq. And although Iraqi forces are showing more willingness to fight than they did when they fled Ramadi in May, they are still struggling to regain territory from the Islamic State. By contrast, the pesh merga, the Kurdish fighters, have successfully forced a broad Islamic State retreat at the cost of 1,500 Kurds killed in action and over 7,000 wounded. The Islamic State, clearly worried by the pesh merga, has responded with chemical weapons.

The Kurdish gains are remarkable given the lack of American support. The United States and its allies have provided the Kurds with obsolete rifles, a few dozen armored vehicles and no tanks. One excuse for refusing to supply Kurdistan with advanced weaponry is that Kurdish fighters haven’t undergone sufficient basic training yet. Meanwhile, the Islamic State, with no formal instruction, operates hundreds of sophisticated weapons that it seized from the Iraqi Army. The Kurds now find that the easiest way to get their hands on quality American equipment is to capture it from the Islamic State.

Added to the lack of weapons is insufficient funds. Many pesh merga fight only part time because their salaries are low and paid infrequently. This saps morale and effectiveness. As one high-ranking official in the Ministry of Pesh Merga Affairs in Erbil explained, “If they stay on the front line for a whole month, they can’t even feed their families.”

Kurdish politics also hold back the pesh merga. Iraqi Kurdistan’s two main political parties, the Kurdistan Democratic Party and the Patriotic Union of Kurdistan, fought a civil war in the 1990s and divided the region into two governments. Although the parties reunited their administrations in 2006, the result has been a tense power-sharing arrangement with long quarrels over any transition of power. At present, for example, President Massoud Barzani is refusing to leave office, even though his term ended on Aug. 20.

Worse, the two parties exercise a divided influence over many pesh merga. Although they have created unified K.D.P. and P.U.K. brigades, these units largely function jointly only on paper. When the fighting starts, one experienced officer remarked, the P.U.K. and K.D.P. soldiers often answer to separate commanders.

If American policy wants to be truly effective, it should do more than just give a few weapons and limited training. Instead, the United States must help Kurdistan to organize, train and equip a nonpolitical Kurdish army. The United States can do this by greatly increasing its support to the Ministry of Pesh Merga Affairs’ program dedicated to building nonpartisan units. The program requires that new recruits join the nonpolitical units as individuals, not party members. The ministry has managed to raise one nonparty brigade, and needs additional support to increase the number of units.

The United States can turn these nonparty brigades into the nucleus of a new Kurdish army by providing the necessary weapons and training to make them effective, which will in turn encourage further recruitment. An American-assisted Kurdish army could make Kurdistan more stable by depriving politicians of control over military units. And a politically independent army reduces the risk of the K.D.P. and P.U.K. turning their guns against each other again. Furthermore, American involvement in the Kurdish army would keep the Kurds focused on the Islamic State rather than any domestic agenda.

Turkey should not be a problem. Although it is currently fighting its own Kurdish population, it has close relations with the Iraqi Kurds. And though Turkey would have much to gain from a stable Kurdistan — indeed, Turkey has strong commercial and security ties with the Iraqi Kurds — the United States should make support for an Iraqi Kurdish army conditional on no bid for independence.

In any event, Iraqi Kurdish leaders are in no rush to seek independence. The Islamic State threat is a brutal reminder of the dangers of going it alone. The local economy is weak, Kurdistan is overwhelmed with refugees and its neighbors will not tolerate its separation from Iraq.

Given what the Kurds have already achieved with so little, a properly trained and equipped Kurdish army would likely inflict significant damage on the Islamic State. This would prevent the Islamic State from entrenching its control over northwestern Iraq and relieve pressure on the Iraqi government. Crucially, that should provide Prime Minister Haider al-Abadi of Iraq with the breathing space he needs to reform and properly rebuild his own forces.

With Russian military intervention in the Middle East growing, President Obama needs to strengthen his Kurdish ally, which has demonstrated an authentic commitment to the anti-Islamic State campaign in Iraq. A Kurdish army able to fight the Islamic State more seriously is the only way to achieve victory without sending American soldiers back to the battlefield.