Noah and I were quibbling earlier on Twitter over whether this is an ominous preview of what Rubio would do as president or just rhetorical window dressing that every hawkish GOP candidate will end up copying. Making Ukraine a member of NATO would, of course, potentially obligate the U.S. under Article 5 to come to its defense on the battlefield against Russia. Whether you think that’s something worth worrying about depends on how you think Vladimir Putin and Marco Rubio would react to a serious bid by Ukraine to join the organization.

We also know, however, that we must never allow our desire for peace to lead us into weakness or inaction. We cannot continue to stand idly by while red line after red line is crossed and ceasefire after ceasefire is violated. Reversing this cycle will require America and our European partners to take a series of important steps…

[W]e must enlarge NATO. Allies need to overcome the roadblocks to enlargement before the next NATO summit — including by inviting Montenegro to join the alliance — and to reaffirm that the open door policy is still intact and applies to any NATO aspirant, including Ukraine if it so chooses. Forged during the effort to bind postwar Europe together and to America, and proven through decades of the East-West conflict, NATO remains central to our security.

That’s from a Rubio op-ed titled “My Vision for Europe” published today in Politico’s European edition. If this is just blather aimed at showing Republican primary hawks that Rubio will challenge Putin directly as president, why is it running in a European newspaper aimed at a European audience? Europeans are less likely to want to confront Putin than Americans are given their greater economic and energy dependency on Russia. If Rubio’s pitching this at an audience overseas, maybe he’s more serious about it than we think.

Which is noteworthy, because Americans aren’t (or weren’t, as of March 2014) eager to fight the battle for Kiev.

Interestingly, in an op-ed published in Politico’s American edition a few weeks before that poll came out, Rubio listed eight steps for punishing Putin’s aggression against Ukraine — but allowing Kiev to join NATO mysteriously wasn’t one of them. Either Rubio’s grown more hawkish towards Moscow as the war in the east has dragged on over the past year or presidential politics have convinced him to flex his muscles even more ostentatiously than he’s used to doing. (Or both of course.) Ukraine, unsurprisingly, also seems more eager to join NATO today than it was when Rubio wrote that earlier op-ed last year. In December they formally dropped their “non-aligned status,” a prerequisite to applying for NATO membership. Just last month the Ukrainian government enacted a new security strategy to bring itself into compliance with NATO membership requirements, with the head of the national security council saying explicitly that joining NATO is “the only reliable external guarantee” of Ukraine’s sovereignty. It used to be that more Ukrainians viewed NATO as a threat than as a potential protector but that view has obviously softened as Putin’s gotten aggressive and the pro-Russian east has drifted away. Go figure that a country that’s massively outgunned by its enemy wants reinforcements from the world’s most powerful military alliance. And NATO, at least in theory, is open to providing that. Noah points out this statement from the organization last June as evidence that Rubio’s op-ed today isn’t saying anything special:

NATO’s door remains open to any European country in a position to undertake the commitments and obligations of membership, and contribute to security in the Euro-Atlantic area…

Allied leaders agreed that Georgia and Ukraine – which were already engaged in an Intensified Dialogue with NATO – will become members of NATO. In December 2008, Georgia and Ukraine were invited to develop Annual National Programmes (ANPs)…

[W]hile no longer pursuing NATO membership since 2010, Ukraine has maintained the existing level of cooperation with the Alliance and has fulfilled the existing agreements. Ukraine has continued to participate actively in the ANP process which plays a key role in determining Allied support for Ukraine’s domestic reform process.

NATO says Ukraine can join and Rubio says Ukraine can join. What else can they say realistically, wonders Noah. “No, we’re afraid of Putin, so Ukraine is out”? If anything, that would give Moscow an incentive to rumble into other eastern European NATO wannabe’s and start a fight before the western coalition can absorb them. Beyond all that, joining NATO is far more complicated than simply saying “we want in.” There are multiple steps involved, including reforming Ukraine’s military and intelligence establishments to bring them into line with NATO standards, and even if Ukraine somehow undertook all of them, their membership bid would still be subject to a vote of all 28 member nations plus ratification by their respective governments. So Rubio, a guy whom I regard as a generally smart tactician, might indeed be blowing smoke here just as Noah says. There’s no downside to saber-rattling in a GOP primary unless the Rand Paul non-interventionist contingent is much bigger than anyone thinks (and it probably isn’t) and there’s also little risk of Ukraine actually joining NATO anytime soon given the hurdles involved. If worse came to worst, European members would probably find a pretext to veto Ukraine’s application for fear of how Putin might react, in which case Rubio could scold them for cowardice while also relaxing in the knowledge that he’ll be under no treaty obligations to send U.S. troops to Ukraine’s defense. (If worse really came to worst and Ukraine somehow ended up in NATO, I suppose NATO leaders could argue that there’s no Article 5 obligation in the current conflict because Ukraine is at war with “separatists,” not with Russia even though it’s supplying and reinforcing those separatists in all kinds of ways.)

But I don’t know. Like I said up top, your view of how alarming this is depends on your view of Rubio and Putin. Would Putin back down if the NATO cavalry decided to ride to Kiev’s rescue? I’m not so sure. He’s invested all of his political prestige domestically in resisting the west and its alleged incursions on Russian sovereignty, most notably in Ukraine. How would he survive politically at home if he turned tail and ran? As for Rubio, I goof on him sometimes as being a McCain for younger generations but it’s not really a goof. I don’t think he’s posturing in his hawkishness; I think he really is eye-to-eye with McCain/Graham-style “today we are all Georgians/Ukrainians” super-hawkishness. Doves like to say that Republican hawks can’t be trusted because not only do they see intervention as the solution to every foreign problem, they see it as the solution to every foreign problem simultaneously, an eight- or nine-front war for freedom on multiple continents. That’s not fair to Rubio, McCain, or Graham, but I think it’s less unfair to them than it is to most other hawks. How fair or unfair voters generally think it is will determine whether Rubio becomes president or not.