Biden was among a series of leaders to assure Zelenskyy of their support. In a phone call on Sunday evening, Biden told Zelenksyy that the US remained committed to Ukraine’s sovereignty and territorial integrity. During the phone call, Zelenskyy invited Biden to visit Ukraine, the presidential office said. “I’m convinced that your arrival in Kyiv in the coming days, which are crucial for stabilising the situation, will be a powerful signal and contribute to de-escalation,” the presidential office quoted Zelenskyy as saying in a statement. Al Jazeera’s Natacha Butler, reporting from Kyiv, said Zelenskyy has been urging for calm amid the uncertainty in the capital. “[He has been] urging people not to panic even though each hour seems to bring something that fuels anxiety,” Butler said. The US warnings, denounced by the Kremlin as “peak hysteria”, come as diplomatic efforts to prevent Russian aggression have failed to yield a breakthrough.