.Putin contacts cross-border strike in Kursk area a 'justification' The Washington PostRussia says Ukrainian troops crossed in to its region as well as introduced 'gigantic strike' CNNHow deep in to Russian region has Ukraine's unpleasant surprise August attack hit? MeduzaUkraine Launches Rare Cross-Border Ground Attack Into Russia The Nyc TimesRussia: State of urgent in Kursk surrounded by incursion DW (English).