By Pavel Polityuk and Jamie Freed KYIV (Reuters) -Ukraine’s biggest airline said on Monday that its insurers had terminated cover for at least some of its aircraft on flights in Ukrainian airspace, as Russia masses a huge military force on the country’s border. Ukraine International Airlines (UIA) said it had received the notification from its insurers as experts said more airlines were expected to avoid Ukraine’s airspace following a U.S. warning https://www.reuters.com/world/europe/us-says-diplomacy-still-open-end-ukraine-standoff-with-russia-2022-02-13 that Moscow could invade its neighbour…