So it's a whole new NATO. Despite Brexit and despite lingering divisions over whether to confront or engage Russia, the transatlantic alliance took some big steps forward at a landmark summit this week in Warsaw.
"We face a serious problem in a revanchist Kremlin and this summit has done an excellent job of addressing it," John Herbst, director of the Dinu Patriciu Eurasia Center at the Atlantic Council and a former U.S. ambassador to Ukraine, said during a panel discussion at the Warsaw Summit Experts' Forum.
By agreeing to deploy multinational military forces to the Baltic states and eastern Poland, NATO has moved from the reassurance of its allies to the deterrence of its adversaries.
Boots on the ground -- particularly American, Canadian, British, and German boots -- should put to rest any lingering doubts that the alliance is prepared to defend its most vulnerable members against a potential attack by Russia.
And even as the buildup in the east addressed the kinetic threat from Moscow, the agreement NATO signed in Warsaw with the European Union was a significant step in addressing the nonkinetic aspects of Moscow's hybrid war on the West.
As effective a military alliance as NATO is, it is ill-equipped to counter threats stemming from the Kremlin's weaponization of globalization: its use of things like corruption, transnational organized crime, international finance, and disinformation to undermine the foundations of Western societies.
Countering these hybrid tactics -- which form a significant part of Russia's threat to the West and are integrated with the Kremlin's military strategy -- requires a coordinated effort not only by NATO, but from the nondefense arms of Western governments as well.
"The EU and NATO cannot afford to go their own ways in dealing with the multitude of challenges they face," Judy Dempsey, a senior associate at Carnegie Europe, wrote.
"They both have expertise that complements the other’s. NATO has hard power, the EU has soft power."
The Gray Zone
So what just went on in the Polish capital was a Very Big (expletive deleted) Deal. Antoni Macierewicz, Poland's defense minister, went as far as to call the summit "a turning point in the history of the alliance."
But at the same time, it was also just the start of a process. The question now is, how does NATO move beyond Warsaw?
With the eastern buildup, it's now clear to anybody paying attention that Article 5, the alliance's collective-defense provision, will be upheld. But can NATO now move beyond Article 5 and find a way to address security issues in its neighborhood?
With U.S. troops set to deploy to eastern Poland, strategically vital Suwalki Gap is being plugged. Can NATO now plug the other security gaps lingering on its periphery?
Specifically, with membership off the table for the foreseeable future for Ukraine and Georgia -- not to mention Moldova -- what happens in the gray zone between NATO and Russia?
"What is NATO's role in relation to those countries? How can NATO project stability beyond its borders?" Herbst asked.
This is far from an academic question as it is in this gray zone, in the lands beyond the Article 5 umbrella, where conflict and instability are most likely to occur.
And any instability on NATO's frontier can easily turn into a security threat for the alliance itself.
"Not giving a membership perspective harms the security environment. And this is true not just for Ukraine and Georgia, but for the wider area," Ivana Klympush-Tsintsadze, Ukraine's deputy prime minister for European and Euro-Atlantic integration, said at the Warsaw Summit Experts' Forum.
So if membership is off the table in the gray zone, and the West isn't prepared to acquiesce to a de facto Yalta and cede these countries to Russia, coming up with a workable alternative is going to be one of NATO's biggest challenges going forward.
Likewise, the agreement between NATO and the EU, which the alliance's Secretary-General Jens Stoltenberg called "a historic deal," is just the start of a process.
NATO and the EU pledged to coordinate their actions and cooperate on a series of security issues, including cyberdefense, terrorism, and countering "hybrid threats" and disinformation campaigns from Russia.
Dempsey of Carnegie Europe noted that the pact could provide "a boost for the Atlanticist wing in the EU" and "make it more difficult for Russia to divide Europe and weaken the transatlantic relationship."
It would also facilitate coordination between European law-enforcement and regulatory bodies -- which would be on the front lines in countering Moscow's hybrid tactics -- and NATO's traditional defense capabilities.
If implemented fully, it would make it easier to form a comprehensive strategy against kinetic and non-kinetic threats.
The operative phrase, of course, is "if implemented fully." Despite having headquarters in the same city and having mostly overlapping member states, NATO and the EU have scant experience in cooperating.
Both have a consensus-based form of decision making that can be slow, quarrelsome, and unwieldy.
Turf wars and squabbles are probably inevitable, and were already evident even before the document was signed.
But if the deal can work, its impact in enhancing security in the transatlantic area could be at least as significant as placing thousands of troops on NATO's eastern frontier.
“Our security is interconnected,” Stoltenberg said. “Together we are a formidable team.”