The two-day NATO summit that opens Thursday in Wales was supposed to be focused on tying up loose ends in Afghanistan and guarding against complacency as the 28-nation alliance shifted from a war footing.
Things have changed since planning for the high-level conference began in late 2013. Though NATO remains on course to end its combat mission in Afghanistan later this year and leaders will still be discussing the alliance's future role there, the security landscape in NATO's backyard has undergone its most profound shift in 25 years. Russia's annexation of Crimea from Ukraine earlier this year and subsequent backing of pro-Russian separatists have caught the alliance off guard.
"This is the most important summit since the end of the Cold War. If it flunks this now, it would be difficult to see how it would recover its reputation," said Jonathan Eyal, director of security studies at the Royal United Services Institute. "The reputation of NATO is on the line."
NATO military commanders have warned that Russia's use of irregular warfare in Ukraine — the arming of separatist militias and sending in secret advisers to incite violence — demands new strategies if such tactics are employed on alliance territory.
In Wales, allies are expected to agree on plans to establish a quasi-permanent, rotational military presence in eastern and central Europe. Those plans are intended to reassure the Baltic states and Poland, wary NATO members on Russia’s periphery, and enhance the alliance’s readiness there.
While Poland has lobbied hard for permanent bases, Germany, for one, has argued they would violate NATO founding documents and further antagonize Russia.
Rasmussen downplayed the lack of permanent basing. "What matters is we have what we need for as long as necessary,” he said. "Bottom line: You will see more visible NATO presence in the east."
NATO is also expected to act on a plan to position military equipment in the region and reshape its response force to be better equipped for rapid-reaction missions.
"I think the main achievement in practical value will be this readiness plan that will increase the exercise and maneuver activity of NATO on its eastern flank," said Jan Techau, an expert on European security policy at the European center of the Carnegie Endowment for International Peace in Brussels. "This means there will be NATO troops on the ground at any given time. It sends the signal NATO needs to send on its eastern border."
Yet stopping short of establishing permanent bases leaves the door open to Russia, which NATO must still try to bring back to the negotiating table, Techau said.
Eyal said there are few practical differences between establishing a permanent base and maintaining a constant troop presence through rotational means.
"I think you will find this is a distinction without a difference," he said. "The rotational forces will be more or less permanent."
Germany's backing of a more robust presence in the region has been a welcome, and somewhat surprising, sign that Europe's major power is serious about potential threats, analysts say.
"The great subplot ahead of the summit is that the Germans, without hesitancy, agreed to join this scheme,” Techau said. “The Germans have actually been lauded here in Brussels."
If there is a general consensus that NATO is prepared to take concrete measures, there remain thorny challenges that could take time to sort out.
Gen. Philip Breedlove, NATO's supreme allied commander, recently asserted that should there be an attempt to stir unrest in NATO territory as Russia has in Ukraine, the alliance would demand an Article Five military response. Article Five is the bedrock alliance principal that an attack on one member requires a collective response from all.
"NATO has not been configured to deal with internal security of its member states," Eyal said. "It is not really obvious how we can use international troops to police what are effectively internal security problems. Does it mean NATO troops can fire on citizens of a NATO country? These are all very grave questions."
NATO will likely address those concerns in Wales in a generic way, but transforming Breedlove's assertion into a sustainable policy will require changes within NATO itself, Eyal said.
Meanwhile, NATO is facing a growing challenge on its southern flank. With fighters from the Islamic State group holding large swaths of territory across Syria and Iraq, allies fear fighters with European and American passports could carry out attacks at home. Turkey, a longtime NATO member, has served as a prime transit route for many of those fighters.
With an estimated 15,000 fighters, including up to 7,000 members who carry European passports, the Islamic State has been described by some as more dangerous than al-Qaida. Several hundred fighters also are believed to be American.
"It’s an immediate threat; that is to say, the fighters who may leave the current fight and migrate home," said Gen. Martin Dempsey, chairman of the Joint Chiefs, during an Aug. 21 news conference.
Adm. James Stavridis, NATO's former supreme allied commander, says the alliance must step forward with a strategy to deal with the Islamic State.
"The United States cannot be the only actor taking on the challenges, and the war weary American public will simply not permit doing so," Stavridis wrote in a recent essay in Foreign Policy. "It is time for the alliance to craft a strategy and work coherently against what is clearly a clear, present, and real danger to the southern borders of NATO. The alliance must act against the Islamic State collectively as they would against any direct threat."
It’s unlikely the NATO summit will generate a collective call to action, but it should offer an indication that the alliance is ready to start grappling with the challenge, experts say. "It is not a sleepy security situation in Europe anymore," Techau said. "All the governments, including the U.S. and Obama, have been accused of not recognizing that. Can NATO send out a message that the West understands the gravity of the situation? This is the test."