Russian authorities believe Chechen militant leader Doku Umarov was amongst the 17 fighters killed in violent clashes in North Caucasus. Three Russian troops also lost their lives during the fighting in Ingushetia. Prosecutors charged Umarov this week with plotting a suicide attack that left 37 people dead at Moscow’s Domodedovo international airport earlier this year. Umarov had claimed responsibility for that blast and for twin suicide attacks on the Moscow metro that killed 40 people last year. Russian officials have mistakenly declared Umarov dead on at least seven occasions before.