How should the United States respond to Islamic State attacks in Paris?

The response from the Republican presidential candidates has been to whip up hysteria over Syrian refugees and hostility toward all Muslims - with rhetoric so repulsive that it shames the country. Ben Carson likened refugees to "rabid dogs," while Donald Trump said he would "absolutely" create a database to track Muslims inside the country.

Much easier to play the demagogue than to present a detailed plan.

To her credit, Hillary Clinton did just that in a speech to the Council on Foreign Relations on Thursday. She called for an intensified focus on Syria (implicitly criticizing President Obama's timid approach).

But to my mind, her most important point was about Iraq. She called for U.S. help for Iraqi Sunni tribal leaders who want to fight ISIS but can't get the weapons and support to do it. That is the one step that, in the near term, might set the so-called caliphate back on its heels.

Why do I focus on Iraq, not Syria? Because I see little chance of routing ISIS in Syria, even with a more resolute policy than Obama's. Airstrikes alone won't do it (although more U.S. special forces on the ground would make them more effective).

Almost no one, certainly not Trump or Clinton, advocates sending tens of thousands of U.S. ground troops. So it is crucial to find Arab allies on the ground who can drive ISIS back with our help.

Right now, our main allies in Syria are Kurds, who are liberating areas that they want to hold in the future. But they can't liberate the heavily Sunni territory at the heart of the caliphate.

Obama missed his chance in 2012 to aid thousands of moderate Syrian Sunni fighters, including many army defectors, who might have developed into a viable force to repel both ISIS and Bashar al-Assad. Those moderates have long since fled, been killed, or joined Islamist militias out of frustration. This leaves Washington without a ground force that can crush the Syrian portion of the jihadi state.

As for enlisting the help of Russia or even Iran in a grand coalition to defeat the jihadis, forget it. Moscow and Tehran hold all the cards in new diplomatic efforts to end the Syrian conflict. Even after the terrorists' downing of a Russian plane, Putin's primary goal - and Iran's - is to bolster the Assad regime, not to defeat ISIS. This practically guarantees that the talks - or any plan to hold Syrian elections - will ultimately fail.

Thus the best chance to squeeze the caliphate, which extends across eastern Syria and western Iraq, is to push from the Iraqi side of the border. This is why it is so important for the administration to stop its shilly-shallying about helping Iraqi Sunni tribal leaders who have been eager to enter the fight for more than a year.

"If Iraq is the only front where we can reduce ISIS, it becomes acutely important to get back the cities there that they control," said retired Col. Richard Welch, who spent more than six years working with Sunni tribal leaders in Iraq.

The U.S. military is familiar with many of these tribal leaders, who took part in the "Awakening" movement during the middle of the last decade. At that time, U.S. forces helped them roll back al-Qaeda.

Last week, I spoke by phone to Sheikh Abdullah al-Yawar of the Shammar tribe, whose base is near Iraq's border with Syria. His tribe has been battling jihadis for more than a decade. Six months ago, when I visited the sheikh, he hoped to get U.S. support to reenter the fight against ISIS, but he says nothing has happened since then.

"We met with Americans last June and told them we had 4,000 volunteers and gave them a list at the end of July," Yawar told me Thursday. "They told me that in two months, they would start training 2,400 and would give us weapons. But since then, nothing has happened, nothing has changed."

Many other Sunni sheikhs are also eager to fight ISIS in Iraq's Sunni heartlands, where the extremists have captured major cities such as Ramadi and Mosul, which is the heart of the so-called caliphate. But the Obama administration insists on funneling weapons and training for the tribes through the Shiite-led central government, which passes on almost nothing to the Sunnis. (U.S. weapons are reaching Iraqi Kurds, but the Kurds - as in Syria - can't go it alone.)

The administration has been holding off for months on aiding Sunni tribes directly, waiting for the Iraqi parliament to pass a national guard law that would subsume Sunni tribal fighters under the national Iraqi army. But Iranian pressure has blocked the law's passage.

The result: Only a couple of thousand Sunnis have joined the struggle. "There are no real Sunni fighters being trained to take back Mosul," says Yawar. "Seriously, there is nothing moving to face ISIS."

This is nuts. As Clinton put it Thursday: "We need to lay the foundation for a Second Sunni Awakening. We need to put sustained pressure on the government in Baghdad to . . . finally stand up a national guard . . . arming Sunni and Kurdish forces. . . . If Baghdad won't do that, the coalition should do so directly."

This is the kind of serious issue candidates should be discussing, not registering all Muslims or banning refugees.