The largest military air exercises in Europe since the end of the Cold War began on Monday, as more than 250 aircraft from across the United States and Germany — fighter jets, bombers and cargo planes — took to the air in a pointed demonstration to Russia of how NATO would respond if the alliance was attacked.
The war games have been planned since 2018, but took on added urgency after the invasion of Ukraine, which alarmed NATO members that lie in the shadow of Russia and jolted the military alliance into reinventing itself after years of torpor.
All but two of the 25 participating nations are NATO members, including Finland, the newest, and the drills are hosted by Germany. Sweden, which is seeking NATO admission, is also taking part, and Japan is an observer.
“Air power is the first response in a crisis,” Lt. Gen. Ingo Gerhartz, chief of the German Air Force, said in an interview at the close of Monday’s exercises — the first of 12 days unfolding at six bases across the country. “We can really react fast, as first responders.”
The exercises, called Air Defender 2023, well before Moscow’s full-scale invasion of Ukraine began last year, but their roots do lie in Russian aggression: the illegal annexation of the Crimean Peninsula in 2014. General Gerhartz, who organized the war games, described that as a “wake-up call.”
After 30 years of shrinking military budgets, air power had become a vulnerability for NATO, but that began changing after the Russian invasion, with leaders in Kyiv billing their country as Europe’s first line of defense against Moscow. The United States eventually agreed to let Ukrainian pilots train on American-made F-16 fighter jets as part of a broader campaign among some NATO states to supply Ukraine with warplanes — not just for the current conflict, but to deter Russia for years to come.
Since the invasion of Ukraine, NATO has shifted from what the military calls deterrence by retaliation — relying on the promise to come to the defense of any member and push back any occupying force — to deterrence by denial, which seeks to prevent an occupation in the first place. That means more troops and equipment based permanently on the Russian border, more integration of allied war plans and more military spending.
Where it might take weeks for warships to sail from the United States, or days to mobilize ground troops in Europe, fighter jets can be scrambled within minutes.
Monday’s flights included a pit stop at an air base in Lithuania, a former Soviet Republic where fear of Russia looms large, specifically to show how quickly warplanes taking off from Germany would arrive. Similar stops will be made in other countries that were once under Moscow’s thumb — Poland, Romania and the Czech Republic.
“In the end, it’s all about credible deterrence,” General Gerhartz said. “We don’t want to be too aggressive, but to show that we are strong.”
In preparation for the war games, the United States sent more than 110 planes and thousands of service members, mostly from National Guard units, over the last two weeks.
“It’s pretty much unprecedented, the amount of aircraft and people that we’ve moved over here in such a short period of time,” said Maj. Will Dyke, a pilot with Kentucky’s Air National Guard.
He declined to describe how the drills might ever be deployed against Russia except to say: “The way we train is to be ready at a moment’s notice.”
Wunstorf Air Base, where the air show took place on Monday, hosts one Germany’s largest military transport units. Cargo and refueling planes — two aircraft workhorses — make up the bulk of its fleet. Fighter jets, the show horses of the sky, are stationed at other bases.
“If you think about a real war, this could be a place where German transport planes would start,” said Maj. Peter Poehlmann, a German officer who oversaw the construction of a new refueling station for jets that could burn though as much as one million liters of fuel each day during the exercises.
Douglas Barrie, a military aerospace expert at the International Institute for Strategic Studies in London, said such exercises must test whether aircraft from so many nations can communicate directly with each other.
General Gerhartz agreed that this remains a big challenge, but recounted a real-life demonstration of coordination between Germany and NATO commanders that took place just days earlier.
Over the course of a week, NATO warplanes had been scrambled 15 times to intercept Russian jets that had strayed close to Baltics states’ airspace, in what Lithuania’s Defense Ministry on Monday said was likely Moscow’s response to the exercises in Germany.
Then this past weekend, German forces tracking a plane from Kaliningrad, a Russian enclave between Poland and Lithuania, quickly handed off command to NATO officials, who deployed fighter jets. Hours later, a commercial airliner over Germany lost radio contact with air traffic controllers, putting General Gerhartz’s forces back in control of what was deemed a domestic alert.
The military exercises come at a turning point for Germany, which has for years fallen short of spending 2 percent of its G.D.P. on defense, the threshold NATO states are supposed to commit. Late last year, the government in Berlin said it expected to meet the 2 percent target by 2025.
But some allies of Ukraine remain skeptical, citing Germany’s lagging weapons deliveries to the country despite Chancellor Olaf Scholz’s sweeping talk of a new era following Russia’s invasion in February 2022. Mr. Scholz has committed 100 billion euros, or $113 billion, to bolster Germany’s armed forces, which have been repeatedly warned about major deficiencies in the state and readiness of its equipment and weapon systems.
If the multinational training drills taking place now are successful, they will show that Germany is willing to take a leadership role in NATO, said Thomas Wiegold, a respected German military blogger.
Stephan Weil, president of the Lower Saxony region of Germany — where the Wunstorf Air Base is located — called the exercise “necessary.”
“That is certainly much clearer today than when it was first planned,” Mr. Weil said. “Since the Russian invasion of Ukraine, we know that the European security architecture, as we have assumed it for decades, no longer functions, and that national defense must therefore have a much greater significance.”
At core, however, the Air Defender drills appear intended to show President Vladimir V. Putin of Russia the risks of pushing NATO too far.
”I’d be very surprised, shall we say, if the alliance wasn’t kind of looking at this as part of its overall messaging strategy,” said Mr. Barrie, the analyst in London.
The American ambassador to Germany, Amy Gutmann, predicted that leaders around the world would most likely be paying attention — and “that includes Mr. Putin.”
Many of the skills that will be tested over the coming days in Germany have been honed by Western pilots and air support crews over the past 20 years, especially in wars in Iraq and Afghanistan, said Col. Rusty Ballard, commander of the Air National Guard’s 182nd Airlift Wing, based in Peoria, Ill.
But at some points on Monday, a three-layered formation of fighter jets, bombers and cargo planes was flying more than 10,000 feet off the ground, and even some of the seasoned pilots found the coordination a little daunting. “Mental gymnastics” was how Flt. Lt. Mark Jenkins of the British Royal Air Force put it.
Lieutenant Jenkins flew a massive A400-M Atlas cargo plane at the center of the wedge-shaped formation, trailed by American and German fighter jets and a U.S. bomber. Two other formations flew above him, at 15,000 feet and 20,000 feet, over more than an hour of maneuvers, air-to-air refueling drills and mid-flight photo ops. Surrounding planes captured images of his cargo jet, which for the occasion sported a tail painted in the colors of the German and U.S. flags.
“I’ve never done anything quite like today,” Lieutenant Jenkins said in an interview later, sitting in the cockpit of the plane. “Having so many other aircraft working together is really unusual.”
He declined to discuss events in Ukraine, but said he was “of course” following the conflict.
“We are practicing a demanding environment,” Lieutenant Jenkins said. “The mantra is, train hard; fight easy.”
Christopher F. Schuetze contributed reporting from Berlin, Steven Erlanger from Brussels and Matthew Mpoke Bigg from London.