Whenever Bernie Sanders is asked about ISIS or Syria, which are among the toughest foreign policy challenges he would face as president, he tends to trot out his favorite (and essentially only) foreign policy position on the Middle East: that the US should put "Muslim boots on the ground" to fight ISIS.

When journalists and experts talk about Sanders's worrying unpreparedness on foreign policy, this is one of the lines they're talking about. It's nonsensical and empty as a solution to ISIS, yet Sanders keeps bringing it up.

But that starts to make a lot more sense when you see that Sanders isn't intending this as an actual plan; rather, it's part of his effort to offer Americans a more emotionally appealing vision of themselves and their place in the world — as well as a promise that they can have this, as well as safety from terrorism, without having to give anything up.

This approach should look familiar: It's the same strategy that Republicans have been deploying — proposing unrealistic and way-too-easy foreign policy solutions not just to duck hard questions about trade-offs and compromises, but as a means to appeal to Americans' feelings about themselves.

The Sanders Muslim army plan

Sanders most recently brought this up at Thursday's debate, where he went so far as to claim this was an actual "doctrine" of Sanders foreign policy:

We have to work in strong coalition with the major powers of the world and with those Muslim countries that are prepared to stand up and take on terrorism. So I would say that the key doctrine of the Sanders administration would be no, we cannot continue to do it alone, we need to work in coalition.

As substantive plans go, this one is almost impossible to parse. The emphasis that the ground troops should be "Muslim" gives the odd impression that Sanders believes what's needed is a religious war, an impression reinforced by his frequent insistence that the war against ISIS is a "battle for the soul of Islam." (It isn't.)

"Muslim," in this case, isn't a reference to an actual pool of troops that the US can direct to advance its policy goals. Islam doesn't have a standing army awaiting instruction from the United States. And there's no reason to think such a force could exist. Many Muslim-majority countries have their own issues with one another that currently make them unable to even hold diplomatic talks over Syria for more than five days in a row, much less form some sort of pan-Islamic army.

Indeed, Sanders's past forays into this subject have included the surprising suggestion that Saudi Arabia and Iran — two countries currently locked in a violent cold-war struggle against one another for control of the Middle East — should join together in the same "Muslim army" to fight Assad.

Maybe it is possible that Sanders just pulled this wacky plan out of thin air and has decided to repeatedly raise it despite being heavily criticized each time, that a senator who has otherwise seemed like a pretty skilled politician suddenly short-circuits whenever foreign policy comes up.

Or perhaps Sanders's "Muslim army" was never really meant to be a plan, much less a "doctrine." And it's not just meant to be a vague enough answer to dodge the question. More likely, Sanders is using this seemingly specific answer to appeal to Democratic primary voters' emotions on something much broader: the way they want to feel about the United States and its role in the world.

Sanders is really talking about what kind of country the US should be, not what it should do

The real key here isn't what Sanders had to say about ISIS during the debate, but what he had to say about the 2003 Iraq invasion. After Clinton discussed her plan to combat ISIS, Sanders responded by talking about the past, not the future:

Let me agree with much of what the secretary said, but where we have a different background on this issue is we differ on the war in Iraq, which created barbaric organizations like ISIS. Not only did I vote against that war, I helped lead the opposition. And if you go to my website, berniesanders.com, you will see the statement that I made in 2002.

Clinton jumped on that, sternly informing Sanders that "a vote in 2002 is not a plan to defeat ISIS." But that's not an accident on Sanders's part. It's exactly the point.

Sanders isn't campaigning on what he thinks the United States should do — he's campaigning on what the United States should be.

His value proposition to voters isn't really that if he is elected, he will withdraw from the Middle East and let the Muslim army fix it. Rather, it's that if he is elected, he will make the US into the kind of country whose newly improved pro-peace identity is the desired end result in itself. The fact that this does not lead to an actual policy for ISIS is irrelevant, because it was never about ISIS, it was about us.

This fits neatly into Sanders's broader narrative that the real problem is the establishment and the status quo — in this case, a hawkish establishment and its militaristic foreign policy — and that overturning it is the solution. Sanders isn't arguing that this would therefore lead to a better policy on ISIS; if he were, he would tell us what that policy is. Rather, he's arguing that this overturning is the goal in itself.

Sanders's message to his supporters: If the US comes to share our worldview, solutions will naturally follow

All this leaves Sanders with a problem, because after San Bernardino and Paris, terrorism is a major issue for voters, and candidates need some kind of answer on how they'll deal with it. And ISIS presents a hard enough problem that any policy, hawkish or dovish, will come with real costs and downsides.

For hawks in either party, the answer is easy: Argue that the root problem is lack of US involvement and argue for more. Hype up the threat such that any downsides become necessary to take on, or imply that expanding US involvement will be both easy and assuredly effective.

But for doves like Sanders, the needle is, in narrow political terms, more difficult to thread. He needs to assure voters they can trust that his policies will deliver the shift toward dovishness they desire, while simultaneously promising them that there won't be a price to pay for this approach when it comes to ISIS. He has to offer something, and that something has to embody dovishness, and the rest will work itself out.

Enter the magical, mystical "Muslim" army.

The reference to "Muslim" troops isn't a way to identify actual real-world allies who will advance US policy goals. Rather, it's a way to promise voters that they can have it all — that they can have their Sanders revolution and be part of a country that embodies their values in the world, while still having some sort of solution for a problem that is bad enough to need one.

There is of course a serious debate to be had about whether US involvement in the Middle East really makes America safer, and about weighing the pros and cons of the US drawing down from the region. But Sanders isn't having that debate.

Instead, he is telling voters that they can embrace an antiwar worldview without having to worry about costs at all, because when they elect a sufficiently dovish and anti-establishment president, that president will help the Middle East's Muslims solve this problem for themselves.

Sanders's Muslim army is the left's equivalent of the GOP's myth of Reagan and the Iran hostages

It's not just Sanders who is using foreign policy to appeal to primary voters' abstract feelings, telling them they can get everything they want without having to pay a price for it. GOP candidates have been doing the same thing. And you can see it particularly when they bring up their party's cherished fable of Ronald Reagan and the Iran hostages.

On January 16, Marco Rubio said on Meet the Press that Obama had "put a price on the head of every American abroad" by allowing a prisoner swap in order to free Washington Post journalist Jason Rezaian and three other US citizens held by Iran. "Our enemies now know that if you can capture an American, you can get something meaningful in exchange for it."

"When I become president," Rubio said, "it will be like Ronald Reagan, where as soon as he took office, the hostages were released from Iran," because "our adversaries around the world will know that America is no longer under the command of someone weak like Barack Obama."

Ted Cruz gave a remarkably similar statement the same day on Fox News, saying that the temporary seizure of the US sailors by Iran was "the direct result of the weakness of this presidency," and that "it’s worth remembering, this same nation, Iran, in 1981 released our hostages the day Ronald Reagan was sworn into office."

That story is not accurate. Iran released the hostages in 1981 because of Jimmy Carter's negotiations, not because of Reagan's toughness. But that hasn't stopped Republican candidates from claiming that when they get elected, they'll have the same Tehran-controlling superpowers as did the Gipper.

But, as with Sanders's promise that a Muslim army is coming to save the day, the accuracy isn't the point. This is not really a story about hostages, or Reagan, or even Iran.

Rather, it's about telling voters that if they have the right kinds of feelings about America — for Sanders supporters, if they desire a dovish and antiwar America; for many Republicans, if they want an American identity of strength and toughness — then those feelings will be so correct that they will brush aside the major foreign policy challenges in the world.

Viewed in that light, the odd foreign policy positions taken by Sanders, Cruz, and Rubio make a lot more sense. The truth is that they're not really offering policies at all; they're offering a sense of identity.

Cruz and Rubio are promising that if elected, they will deliver not just faraway foreign policy victories but also feelings of personal pride and strength to any American who wishes to see himself as part of something powerful enough to dictate terms to the world.

Sanders, by the same token, is promising that if he becomes president, he will let Americans enjoy feelings of peacefulness and moral righteousness, as well as a reprieve from feelings of shame that US military interventions inspire in some Americans, without any of the messy compromises that come with getting involved or not involved in Middle Eastern conflicts.