Kyiv: A defiant Ukrainian leader urged citizens to celebrate a “Day of Unity” on Wednesday, as Washington warned once again that Russia remains poised to launch a devastating assault. President Volodymyr Zelensky chose the date for what he hoped would be a patriotic outpouring after US reports suggested Russian forces could attack as early as February 16. An intense diplomatic campaign is underway to head off the crisis triggered when Russia deployed more than 100,000 troops on Ukraine’s borders, backed with fleet reinforcements and powerful artillery and missile systems. On Tuesday, there were hopes for a breakthrough as President Vladimir Putin met Germany’s Chancellor Olaf Scholz to explore a route to a negotiated solution and Moscow said it had begun to pull back some forces. But US President Joe Biden — who has ordered Washington’s embassy in Kyiv closed and urged Americans to leave Ukraine — demanded that Russia prove its good intentions with a verifiable withdrawal. “Analysts indicate that they remain very much in a threatening position,” Biden said, in an address on the crisis. “The United States is prepared no matter what happens. We are ready with diplomacy,” he said. “And we are ready to respond decisively to the Russian attack on Ukraine, which is still very much a possibility,” he said, warning of “powerful sanctions”. Earlier, in the first announced withdrawal from among the troops Russia massed on the Ukrainian border, the defense ministry in Moscow said some soldiers were returning to bases at the end of planned exercises. Western leaders have accused Moscow of positioning the troops in advance of a possible invasion of pro-Western Ukraine, warning that any attack would be met with severe economic sanctions. After meeting Scholz in Moscow, Putin said Russia “of course” did not want war, and was willing to look for solutions with the West. “We are ready to work further together. We are ready to go down the negotiations track,” Putin told a joint press conference with Scholz. In response, Scholz said: “That we are now hearing that some troops are being withdrawn is, in any case, a good sign.” “For Europeans, it is clear that lasting security cannot be achieved against Russia but only with Russia.” Moscow released a few details about the troop withdrawal. In Brussels, NATO chief Jens Stoltenberg said while there was not yet “any sign of de-escalation on the ground” there were “grounds for cautious optimism”. The crisis — the worst between Russia and the West since the Cold War ended — reached a peak this week, with US officials warning of a full-scale invasion — perhaps on Wednesday. Zelensky reacted with sarcasm to the warning, and declared Wednesday a “Day of Unity”. “Serious external and internal challenges have arisen, which require responsibility, confidence, and concrete actions from me and each of us,” he said. “But our state today is stronger than ever,” he vowed. On Tuesday, Ukraine said the websites of the country’s defense ministry and armed forces, as well as two banks, had been hit by a cyberattack that could have Russian origins. “It cannot be excluded that the aggressor is resorting to dirty tricks,” Ukraine’s communications watchdog said, in reference to Russia. In a separate move likely to anger Kyiv, Russian lawmakers on Tuesday voted to urge Putin to recognize two breakaway regions in eastern Ukraine as “sovereign and independent states”.