summarize most important info in short bullet list: When Russia invaded Ukraine a year ago, one of the biggest successes they achieved initially was in southern Ukraine. Within a few days Russian troops attacking from Crimea had seized an area of Ukrainian territory bigger than Switzerland. Ukrainian authorities are yet to explain what went wrong in the south in those early days. To help uncover what happened, the BBC has spoken to military officers, politicians and activists. On 22 February 2022 at 19:15, the secretary of Ukraine's security council NAME_1 received a red folder with secret documents. They warned that the president's life was under imminent threat. Immediately, Mr NAME_2 contacted the head of the security services, the interior minister, prime minister and President Volodymyr NAME_3 himself. But Ukraine's leadership stopped short of declaring martial law, for now. There was no mobilisation of troops. Just a few weeks before, Ukrainian authorities had described Western warnings of Russian invasion as "manipulation" and called on everyone to remain calm. Mr NAME_2 says the government had detailed information about the planned invasion, including its dates. "We expected it on 22 February," he explains, rolling out a secret map of the Kyiv region. Taken from a Russian commander, he says it confirms intelligence reports that Russia's initial plan was to invade two days earlier than they actually did. "Our goal was to avoid any panic inside the country. So, it was crucial to keep it all secret." Wrap the entire output in JSON format.
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