In the wake of last week's terrorist attacks in Paris, the Republican presidential candidates have been very specific about two ideas: President Obama should describe the U.S. as in a war against people who practice a radical form of Islam, specifically invoking that religion; and that the U.S. should bar refugees from Syria from resettling here.
But with the exception of South Carolina Sen. Lindsey Graham, they have been very vague on one key question: Should U.S. troops be deployed to Iraq and Syria to fight ISIS and, if so, how many?
"I think it's premature to say the exact numbers," Florida Sen. Marco Rubio told ABC News on Sunday, when asked if he agreed with Graham's proposal to send 10,000 additional American troops to fight ISIS. "I would say this: I think that we need to begin to work more closely, for example, with the Sunni tribes in Iraq who do not want to work under the thumb of the central government in Iraq."
"We need to intensify our efforts in the air - and on the ground. While air power is essential, it alone cannot bring the results we seek. The United States - in conjunction with our NATO allies and more Arab partners - will need to increase our presence on the ground," former Florida Governor Jeb Bush said in a speech on Wednesday in South Carolina.
"The bulk of these ground troops will need to come from local forces that we have built workable relationships with," Bush said, declining to spell out any suggestions for the number of U.S. troops or who would make up these "local forces."
"We already have American troops on the ground. The question is how many do we need, and do we need special ops forces that can work in conjunction with the Kurds and with the Iraqi forces, and as we begin to win we will find a great deal more cooperation from some of the other countries throughout the region," neurosurgeon Ben Carson said in an interview with a Las Vegas television station on Sunday, sounding more like a commentator than a potential president and not laying out how the U.S. would "begin to win."
This approach by the candidates has obvious shortcomings, with Republicans focused on policy solutions that are very limited. Keeping refugees out of the U.S., as the Republicans lawmakers across the country and some Democrats have urged, might be part of a broader strategy to prevent an ISIS attack here, but does little for limiting the growth of terrorist networks abroad. Invoking the phrase "radical Islam" could help more accurately define the problem that the world is facing, although both President George W. Bush and now Obama avoided that phrase, arguing it would alienate parts of the Muslim world without any obvious policy benefit.
Obama has been reluctant to send American forces to fight ISIS, so the U.S. has sent 3,500 troops to work with the Iraqi forces and recently deployed 50 special operations personnel in Syria.
But Obama has acknowledged the limits of his approach. He has suggested that the conflict with ISIS is a long-term one for the United States, with few short-term answers. And he is strongly opposed to putting a larger American force into the region.
"Let's assume that we were to send 50,000 troops into Syria. What happens when there's a terrorist attack generated from Yemen? Do we then send more troops into there? Or Libya, perhaps? Or if there's a terrorist network that's operating anywhere else -- in North Africa, or in Southeast Asia? So a strategy has to be one that can be sustained," the president said in remarks on Monday.
The Republican candidates, on the other hand, have used bellicose rhetoric in describing their plans to fight ISIS, arguing that can be done with an aggressive approach led by a more assertive president.
Bush has emphasized the need to "take out ISIS with overwhelming force," but has laid out a series of ideas that are unlikely to result in that outcome.
"Declare a no-fly zone over Syria. Directly arm the Peshmerga forces in Iraq. Re-engage with the Sunni tribal leaders. Embed with the Iraqi military. Be able to create safe zones in Syria. Garner the support of our European allies and the traditional Arab states," Bush said Sunday on NBC's "Meet the Press."
"We must join with our NATO allies and importantly with allies in the region as well. That would be the Turks, the Jordanians, the Egyptians, the Gold states, the Saudis to organize an international coalition to defeat ISIS on the ground in its heartland," Ohio Gov. John Kasich said in a Wednesday foreign policy speech.
The U.S. is already working with European and Arab nations and the Iraqi military in fighting ISIS. A no-fly zone would not affect directly ISIS, which conducts its operations on the ground, as critics of that approach note.
The Republican candidates have repeatedly suggested they would not be willing to propose a number of U.S. forces in Iraq and Syria without learning what American generals there want. Current U.S. generals are of course not in the position of offering freelance advice to presidential candidates. But many officials familiar with the military and U.S. policy abroad, like retired general Stanley A. McChrystal, speak publicly regularly and would no doubt offer credible advice.
This deference to the generals seems designed by the candidates to avoid discussing specific troop numbers.
Nearly all of the Republican candidates say they want more people fighting ISIS, as long as they are not American troops. Experts say this is an unrealistic approach. There may be dozens of nations in a coalition fighting ISIS, but much of the military and intelligence capability comes from the United States.
"This coalition is largely B.S., it is us," says Danielle Pletka, senior vice president for foreign and defense policy studies at the conservative-leaning American Enterprise Institute.
"It is going to take leadership and commitment from the United States ... and thus far, we don't want to do it," she added, speaking to group of chief executives at an event organized by the Wall Street Journal on Tuesday.
At the same event, Strobe Talbott, who was a deputy secretary of state in the Clinton administration and now runs the Brookings Institute, said, "the president is going to have to take a deep breath and consider not just safe zones, but American forces on the ground."
Talbott's emphasis on American ground forces puts him in some ways to the right of Republican 2016 candidate U.S. Tex. Sen Ted Cruz, who has suggested Kurdish forces are the key to fighting ISIS.
The Democratic presidential candidates have largely avoided criticizing Obama, but they too have been rather vague in their ideas to combat ISIS. In a recent presidential debate, ex-Maryland Gov. Martin O'Malley called for "new thinking" on the issue, but then offered comments like the U.S. "must rise to this occasion in collaboration and with alliances to confront it. And invest in the future much better human intelligence so we know what the next steps are."
He did not list any clear next steps.