Kherson (Ukraine) (AFP) – President Volodymyr Zelensky on Monday said it was “impossible to kill Ukraine” as he hailed the liberation of city of Kherson in a surprise visit. NATO secretary general Jens Stoltenberg meanwhile cautioned that Ukraine was facing difficult months ahead and Russia’s military capability should not be underestimated, despite the takeover of Kherson, the only regional capital that Kremlin troops captured in nine months of war. The Ukrainian presidency distributed images of Zelensky singing the national anthem with his hand over his chest as the country’s blue and yellow…