Secretary of State Rex Tillerson is scheduled to skip an April meeting of NATO foreign ministers to meet with Chinese President Xi Jinping in Washington, giving a cold shoulder to many of Washington’s closest allies. Experts on Washington’s delicate diplomatic relationship with Europe had surprisingly undiplomatic reactions.

“Unprecedented,” Ivo Daalder, former US ambassador to NATO and current president of the Chicago Council on Global Affairs, said of Tillerson’s decision.

“US allies are alarmed and worried,” Jenny Mathers, a Russia expert at Aberystwyth University, told me.

“An unmitigated disaster,” Steve Saideman, a professor at Carleton University who studies the NATO alliance, wrote in a note.

The basic issue, according to these experts, is that America’s allies are already worried about Trump’s commitment to NATO given his long public record of trashing the alliance. What they need right now is reassurance, through word and deed, that the US will honor its commitments to defend NATO members from attack by Russia or other hostile powers.

Tillerson is sending literally the opposite message. Beyond skipping the meeting, America’s top diplomat will meet with Russian President Vladimir Putin later in April, a move likely to reinforce European fears that Trump is willing to weaken NATO in order to bolster ties with the Kremlin. NATO only functions if members believe they can trust other governments to honor the alliance’s core principle that an attack on one is an attack on all. Tillerson’s decision to skip the meeting could weaken NATO just when a Europe riven by fears of a rising Russia and a fading European Union are desperately hoping the alliance will remain stable.

Apparently, Tillerson and NATO are working to try to reschedule the meeting to accommodate the secretary’s schedule. Success would avert much of the damage, but it’s not guaranteed. And if he still does miss the summit, the consequences could be significant.

“When it comes to meetings, which are the lifeblood of the policymaking process at NATO, showing up is 85 percent of the job,” Daalder says. “And he’s not showing up.”

Tillerson missing this meeting directly weakens the NATO alliance

The meeting Tillerson planned to skip, called the “NATO ministerial” or just “ministerial” for short, is a biannual meeting of foreign ministers from all 28 NATO countries. They don’t spend the time chitchatting idly; the ministerial is where NATO countries hammer out their plans for the alliance in the coming year, which then get finalized in a May NATO summit attended by heads of state.

“Ministerials set NATO's agenda, and the US is the primary agenda setter,” Saideman explains. “So no secretary of state means NATO will not have much momentum for the next NATO summit.”

That means Tillerson missing the meeting isn’t just a diplomatic snub. Developing a coordinated, alliance-wide Russia policy will be harder without this kind of top-level contact. So, too, will Trump’s oft-stated goal of making NATO members spend more on defense (all NATO members are supposed to spend 2 percent of GDP on their militaries, a target that only five member states meet).

This is why the excuse given by the State Department spokesperson — that Tillerson planned to meet with allied representatives at a counter-ISIS summit in Washington on Wednesday — doesn’t pass muster. That meeting simply does not have the status or significance of a NATO ministerial for the alliance itself, plus there probably isn’t much time to talk about non-ISIS business there.

“There’s a real sense that other Western countries are throwing their hands up in dismay”

Refusing to attend a meeting of this significance also sends a powerful signal, especially since Tillerson is missing it to meet with Xi and then Putin directly afterward, Tillerson is telling allies that they rank lower on the priority list than America’s traditional rivals.

In prior visits, Trump administration officials had worked hard to assure allies that this was not the case. In February, Vice President Mike Pence and Secretary of Defense James Mattis traveled to Europe to tell them that America was still all in on NATO. Pence, in a public address, called America’s commitment to the alliance “unwavering.”

Tillerson skipping the ministerial would throw this hard work out the window.

“It will be read in Europe as a very strong statement of reduced interest in NATO, no matter what Secretary Mattis says, no matter what the vice president says,” Daalder says.

This is also one of a number of recent insults toward NATO allies. In the past week alone, President Trump refused to shake German Chancellor Angela Merkel’s hand at a White House meeting and the administration accused British intelligence of spying on Trump during the campaign at Obama’s behest. If you were a NATO ally looking at all these gratuitous insults, you could be forgiven for believing that you couldn’t trust the Trump administration to have your back in the event of an actual high-stakes crisis.

“After crapping on Merkel during her visit and after, this is more destruction of allied relationships,” Saideman says. “This is awful not just for optics but for actual relations with our allies.”

Signals matter, for allies and for Russia

To understand why this is so unsettling, you need to understand a little bit about how NATO actually works.

When NATO was created in 1949, it was built around a promise that an attack on one country would be considered an attack on all countries. You invade Poland, you start a war with the United States.

Now, NATO doesn’t have the power to force the United States or any other power to defend anyone else. Article 5, the provision in the NATO treaty that provides for collective self-defense, isn’t binding on America in the way the US Constitution is.

Instead, Article 5 works by credible commitment: If the United States and its allies signal that they are fundamentally committed to the NATO treaty, then it sends a signal to Russia and other hostile powers that America’s military might will be used to defend any members of the alliance that come under attack. This deters Western adversaries from launching wars or any other kind of military adventurism in a US-aligned state.

This is why the symbolism of Tillerson skipping the meeting would matter, beyond the practical consequences. NATO won’t be able to deter an expansionist Russia if Putin concludes that Trump isn’t genuinely committed to defending a member nation that he chooses to attack. Perception, in this case, is reality.

“There’s a real sense that other Western countries are throwing their hands up in dismay,” Mathers says. “They’re adjusting themselves to the reality that this administration may very well do what it says in being more isolationist.”

That concern is most palpable in the Baltic NATO members: Estonia, Latvia, and Lithuania. These countries were former Soviet republics, and Putin seemingly believes they still ought to be Russian possessions. He has routinely screwed with them: kidnapping an Estonian security officer in 2015, sending Russian warships into Latvian waters 40 times in 2014, and repeatedly buzzing their airspace with Russian jets.

In these Baltic states, then, there’s a fear that Russia will interpret signals like the ministerial snub as a sign that it can step up its adventurism in their countries — just to test the limits of how far the new administration will let it go. We don’t know exactly where this could lead, but the chances are it’s nowhere good.

“I’m not predicting that Russia is going to go to war tomorrow because of this,” Daalder says. “But the chance that it will probe ... is enhanced.”

Nobody knows if this is incompetence or intentional

The strange part, in all of this, is that Trump hasn’t really done much to change Obama’s formal policy toward Russia. Sanctions on Russia are still in place, US troops are still in the area, and there’s no sign that the US is going to start directly cooperating militarily with Russia in the fight against ISIS in Syria and Iraq.

Most notably, the US military is deploying 900 new troops to Poland in April as an explicit attempt to shore up NATO’s deterrent against Russia. "The purpose is to deter aggression in the Baltics and in Poland,” Lt. Col. Steven Gventer, the commander of the deployment, said at a press conference on March 20. “We are fully ready to be lethal.”

So while US allies are likely to interpret Tillerson’s snub as a sign of reduced US commitment to NATO, it’s possible that’s not actually what he was trying to convey — an interpretation reinforced by the last-minute efforts to reschedule the ministerial.

Tillerson is not a career diplomat; his last job was running ExxonMobil. He’s been kept away from key high-level meetings. He doesn’t have any background in NATO politics, and might very well not understand the significance of the ministerial meeting or how allies would interpret a snub.

Nor does he have much of a staff to lean on: the deputy secretary of state, the No. 2 position, and a host of other high-level slots remain unfilled. What close staff Tillerson does have isn’t enough to do the job, which means he might not be getting the advice he needs to avoid rookie mistakes. The secretary of state could, very plausibly, have dealt a blow to NATO without meaning to.

“Tillerson has surrounded himself ... with a bunch of folks who don’t understand how the State Department works or what it’s supposed to do,” Ilan Goldenberg, a high-level staffer during the Obama administration and current senior fellow at the Center for a New American Security, says. “You have this little cocoon of inexperienced people advising the secretary, and he’s making basic mistakes.”

It’s also possible, of course, that this is intentional, the first step in a broader Trump administration pivot away from NATO and toward Russia. The problem is that it’s tough to tell the difference from the outside; incompetence and intentional action would, in this case, lead to the same outcome (Tillerson skipping the ministerial).

We’ll probably get some more clues down the line, as this administration is only two months old, and the rescheduling meetings are certainly a hint in one direction. But the problem right now is that other countries have to make policy right now, and they make it based on what they see. And what they see is the most powerful country on earth in disarray, committing to policies at odds with historic American commitments and, at times, its own stated objectives.