Thousands of troops, tanks and artillery pieces massed along Europe's eastern border with Russia and Belarus on September 14, and for nearly a week, guns rattled off ammunition, cannons boomed and tanks rolled across the countryside.
This may sound like an invasion, but it wasn't. It was Russia's most recent military war game, code named Zapad 17, and some experts believe it could be Russia's largest since the end of the Cold War. Russian officials say the exercise included approximately 12,700 troops and hundreds of tanks, artillery pieces and ships. Western experts say that number of troops that took part is more likely between 70,000 and 90,000.
"These exercises are clearly intended to create a certain amount of unease in the West," Michael O'Hanlon, a senior fellow at the Brookings Institution who specializes in defense strategy, told Circa. "I think the confusion, the ambiguity and the low-balling by Russia of the number of troops is actually intentional. Not just because they are trying to avoid compliance with specific rules of European transparency on military affairs, but because they want us to be a little bit antsy about just how big and how threatening this exercise might be."
What's particularly concerning about Zapad 17 is Russia's partnership with Belarus, a country that O'Hanlon says has long been in the Russian camp. Belarus is strategically crucial for Russia because it shares a border with Lithuania, Latvia and Poland -- all NATO members. It also sits just north of Ukraine, in which Russia has been meddling for years.
So is Russia preparing to invade eastern Europe? Probably not.
It's more likely a scare tactic in Russia's ongoing feud with the West, according to many experts. That said, past Russian exercises have preceded conflicts. Russian forces performed a large exercise prior to invading Crimea in 2014. They engaged in another near Georgia in July 2008, just months before war broke out.
"I think Russia wants that fear to unsettle us," said O'Hanlon. "I don't really think Russia knows what the next step in this process would be, just what they are trying to achieve as an end state. But in the short term, they want us to be nervous about the security of eastern NATO member states. They want us to be reluctant to bring more countries into NATO. And they'd love to weaken NATO by causing internal dissent within the alliance about just how seriously to take this potential threat."
Russia and Belarus claimed the exercise was purely defensive in nature. NATO military chief Army Gen. Curtis Scaparrotti conceded that past exercises indeed have been defensive, but with a "rehearsal" attack portion later on.
"That's worrisome if you're a NATO country on the border," Scaparotti said in an interview with the Washington Post.
There were some incidents that raised eyebrows. A Russian helicopter accidentally fired on a group of observers watching the exercise near the Estonian border, reportedly injuring three. The Kremlin blamed the attack on a faulty targeting device. Additionally, Russian jets reportedly violated Lithuanian air space, which the Kremlin also dismissed, claiming they were avoiding storms.
Nothing detrimental has resulted from Zapad 17 thus far, but that doesn't mean it should be taken lightly.
"Everybody should be a little bit afraid. We have the worst state of relations between the Western world and Russia since the Cold War ended," said O'Hanlon, noting that the state of relations has been likened to a new Cold War that could lead to a world war.
It may sound hyperbolic, but he noted that countries have gone to war over less.
"Let's not forget that World War I began over the assassination of an archduke in Bosnia, of all places," O'Hanlon said.