When Boris Johnson finally announced he would step down as UK Prime Minister on Thursday, after desperately trying to cling onto power despite a historic government rebellion, his decision sparked a sense of relief across Westminster. In Kyiv, it was met with despair. Johnson has been one of the most vocal supporters of Ukraine as it tries to defend itself against Russia's unprovoked assault, and his departure stirred up fears that the UK's support for the country -- worth £3.8 billion ($4.6 billion) so far this year -- might start to dwindle. With the whole Western world united behind it,...