On Feb. 24, Russia launched a war against Ukraine after months of rising tensions and warnings from Western countries about a potential invasion. Land, air, and sea attacks throughout Ukraine have killed dozens and left hundreds more injured. It's also led to a refugee crisis, with hundreds of thousands of Ukrainians fleeing their homes. In response to the attacks, the US and other Ukrainian allies have imposed economic sanctions against the Kremlin. But with this being the biggest conflict Europe has seen in decades, it's left many wondering… Why did Russia invade Ukraine in the first place? It boils down to one person: Russian President Vladimir Putin. Let’s be clear, many Russians did not want an invasion of Ukraine. In an address to the nation on the day of the first attack, Putin said he was launching a “special military operation” to protect Russian speakers in two breakaway regions in eastern Ukraine (aka: Donetsk and Luhansk). Claiming that separatists in the area had called for backup. He said the goal of the operation is to stop a “genocide” against Russian speakers. And for the “demilitarization and denazification of Ukraine.” (More on that below.) But experts and President Biden said Russia's invasion is part of a larger plan. And that Putin's likely goal is to "reestablish" the USSR. Quick reminder: Ukraine was part of the Soviet Union before it collapsed in 1991. And part of Russia’s latest attack is to keep its friends close, and Ukraine closer. For years Russia has tried to keep Ukraine out of NATO — a Western military alliance that Ukraine has been eager to join. But Putin said it would be a threat to Russia’s security. He has repeatedly said that Ukrainians and Russians are "one people." And tried many times to get a foothold in the sovereign nation. Learn more about the history and buildup leading to the attack here. You mentioned “genocide” and “denazification.” What does Putin mean by that? The Russian gov says that Ukraine's fallen into the hands of neo-Nazis who are committing genocide against ethnic Russians. It’s part of a larger Russian disinformation campaign to create support for an invasion in Ukraine. But experts say that Putin’s claims are baseless. Ukrainian President Volodymyr Zelenskyy, who’s Jewish and lost three family members in the Holocaust, disputed Russia’s claims. “How can I be a Nazi?” he said. “Tell my grandpa, who went through the whole war in the infantry of the Soviet Army and died as a colonel in independent Ukraine.” How far will Russia go? No one’s really sure. Which is part of what makes the situation so volatile. At first, Putin said the "operation" would focus on eastern Ukraine. And that he wouldn’t occupy the country. But Russia has clearly gone beyond that, targeting a number of cities across Ukraine with attacks that could amount to war crimes. For now, Russian forces don’t seem ready to de-escalate. And Putin has hinted at nuclear threats since the start of the invasion. But, Russia's president is facing some pretty big obstacles. Like fierce resistance from Ukrainian soldiers that have slowed down Russia's advances. And major economic sanctions and isolation from Western nations — which has already wreaked havoc on Russia's economy. theSkimm Russia’s invasion of Ukraine has left the world shaken, and shown how fragile democratic systems can be. But it’s still unclear if the ongoing pushback against Russia is enough to stop its deadly attack on its neighbor. More Coverage of the Russia-Ukraine Conflict Still have more questions about the conflict? We've got you covered with... The Daily Skimm. Sign up to get the latest news on what's happening in Ukraine in your inbox every morning. "Skimm This." Listen to our news podcast for expert context on the crisis. Our explainers on Russia and Ukraine’s complicated relationship, and how SWIFT could play into Russia-Ukraine peace talks. Verified resources in case you’re looking for ways to help Ukraine Expert advice on what to do if the Ukraine crisis is weighing on you. Updated on March 1 with our additional coverage of the crisis.