However you want to define "war," Americans believe we're headed for it.

A new NBC News/Wall Street Journal poll shows that, despite White House assurances that it has no plans to put U.S. troops on the ground to fight the Islamic State in Iraq and Syria, 72 percent of people think that's precisely what we're going to get.

Perhaps most interesting, the American public in large part would support such a move. The same poll shows that a plurality (45 percent) of people would support "boots on the ground" if it's what military commanders recommend, vs. 37 percent who would stand opposed.

So how is it that an American public that is supposedly so war-weary is suddenly so supportive of sending troops -- even without military commanders or the president having asked for such a thing?

Part of it is that nature of the enemy. While Americans have balked at getting involved in a series of confrontations overseas in recent years, none of them have involved something that is perceived as such a direct and imminent threat to the United States as the Islamic State. Don't get us wrong: The American public is and was war-weary. But it was mostly weary of getting involved in conflicts in which American interests weren't clearly at stake.

This is different. Two-thirds of Americans consider the Islamic State a "major threat" to the United States.

It's also important to put the 45/37 split in context. It might seem surprisingly high because of Americans' war-weariness and the fact that there hasn't even been a request for ground troops. But as we've written before, this actually would be a very low level support for a new military campaign.

As the below chart from Gallup shows, it's unusual not to have overwhelming majority support for a military campaign at the outset.

Gallup pegged current approval for U.S. efforts in Iraq and Syria at 60 percent. Even without putting troops on the ground, that ranks among the least-popular nascent efforts on this list. And if and when it came to sending ground troops to Iraq and Syria, a 45/37 split would be pretty underwhelming.

Again, the war-weariness is clearly still there.

At the same time, such a request would entail making a public case to the American people, at which point support could rise quite a bit -- especially given how serious a threat the Islamic State is considered. So the numbers we're seeing today only provide so much insight.

This is a very early poll testing a very hypothetical set of circumstances, but it's also a very plausible one -- as nearly three-quarters of Americans seem to believe. And although it might seem like Americans are becoming pretty amenable to putting boots on the ground, it's clear that the wars of the past decade-plus still weigh heavily on that decision.