BRUSSELS — With a deafening thunder, the first NATO AWACS surveillance plane pierces the milky morning sky over Germany's Geilenkirchen base, on its way to monitor the skies above Ukraine.
Listen very carefully, and you can also hear the NATO alliance roaring back into the geopolitical arena.
Quite a turnaround for a 65-year-old military organization increasingly condemned by many as a costly anachronism.
The crisis around Ukraine "is providential from the point of view of NATO," said Nick Witney of the European Council on Foreign Relations. "It gives it a new lease on life."
NATO Secretary General Anders Fogh Rasmussen left Tuesday for talks in Washington bound to center on the evolving crisis. And at the same time U.S. Vice President Joe Biden arrived in Poland in a clear show that the United States, and NATO, stands together with its worried partners in the military alliance.
On the same day, Russian President Vladimir Putin approved the annexation of Crimea and warned he does not want any military organization to be active at Russia's "fence."
"At a moment like this, we all appreciate in a special way the fact that we are in NATO," Polish President Bronislaw Komorowski said recently.
The NATO alliance was forged in the wake of World War II, when the West was fighting the Soviet Union in a direct confrontation between free-market capitalism and Communism, an ideological battle that basically sliced Europe in two.
Essential during the Cold War when it faced the Soviet-backed Warsaw Pact in a standoff involving thousands of nuclear missiles, NATO's role has been questioned since the demise of Communism, and even more so after the Balkan wars of the 1990s.
It has expanded to include many former Warsaw Pact members, and stretched its geographical title of North Atlantic Treaty Organization to the limit with far-flung operations in Afghanistan and Libya. But it was Putin who gave it fresh credibility with his incursion into Ukraine's Crimean Peninsula.
On top of the deployment of the AWACS planes, Britain decided Monday to send British Typhoon jetfighters next month to boost NATO's Baltic air policing mission. The U.S. Air Force currently patrols air boundaries of the Baltics with 10 F-15C Eagle fighter jets.
Last week, the United States deployed some 300 troops and a dozen F16 fighters to Poland for joint exercises, but also to support its NATO partner.
Suddenly, nations that were once controlled by Moscow crave NATO's protection.
"It would be hard to imagine any stronger guarantees of Poland's security," Komorowski said as his country marked 15 years of NATO membership last week.
Ukraine proves to be a case in point. It is a NATO partner, but not a member, so it does not fall under the Article 5 collective defense clause that states that an attack on one ally is considered an attack on all.
If Ukraine had had such protection, NATO would have had to ensure military protection and go to war if necessary.
"Yes. Yes — there is no question about that," said Steven Blockmans of the Centre for European Policy Studies. "If Ukraine were a NATO country, we would be talking about the invasion and occupation of a part of a country without that country's central government's consent."
If Russia were to do the same thing in a NATO country, such as one of the Baltic states that have a sizeable Russian minority, "Article 5 would describe an obligation to come to the defense of (the country), including the use of armed forces," Blockmans said. "If Russia were to take that gamble, there would be no stepping back from the brink of war for the NATO allies."
Such is the fear of Russia that some now want NATO to send ground troops to the Baltic states to counter Moscow's threat.
"Increased presence of NATO allies in our region would make sense, both militarily as well as serving as a deterrent," Estonian Defense Minister Urmas Reinsalu said on the same day the AWACS took flight. "Living next door to the Big Bear means that we need a solid defense platform."
It all makes for a markedly changed reality in Europe, where trade and cooperation between East and West seemed the future over the past decade. Now, the continent is staring at confrontation.
Witney of the foreign relations council said there is little alternative at this stage.
"It is necessary to respond in that sort of way. Otherwise, it is possible that Putin and those around him could misinterpret it as a sort of terminal weakness of the West."
"It will be a resumption of institutional attitudes that will last for a good many years."
Jari Tanner from Tallinn, Monika Scislowska from Warsaw and Juergen Baetz from Berlin contributed to this story.