should be made non-optional
Любовь Ширижик (Старший редактор отдела «Силовые структуры»)
，推荐阅读PDF资料获取更多信息
Виктория Кондратьева (Редактор отдела «Мир»)
The US says six of its F-15 jets were "mistakenly shot down by Kuwaiti air defenses", with all crew in a stable condition.