Ukraine has a sizable population of Russian speakers, particularly in the eastern regions, and the ban may be viewed as discriminatory towards this minority.
NATO and defence leaders from about 50 countries met at the American Ramstein Air Base in Germany on Friday, the latest in a series of arms-pledging conferences since Russia invaded Ukraine 11 months ago.
Along with Denys Monastyrsky, his first deputy Yevgeny Yenin and state secretary Yuriy Lubkovich were among 8 government officials who were travelling in that helicopter.