evidence: Zelenskyy also spoke directly over the phone with U.S. President Joe Biden late Wednesday. Biden said in a statement shortly after the call that he told the Ukrainian president he "condemned this unprovoked and unjustified attack by Russian military forces." [...] Later in the day, an official Telegram messaging app channel for Kyiv, Ukraine's capital, advised all non-essential workers to "stay at home and be prepared to go to the shelter if the sirens are turned on." Schools were also closed Thursday, the message said, while hospitals would work in an "intensified mode." [...] "Dear Kyivans! Ukraine is attacked by the aggressor. The roar of shells can be heard in Kyiv. The worst enemy now is panic. We do not lose endurance," Klitschko said, while warning residents to prepare themselves to leave in their homes if needed.