Iran tipped off Russia about the possibility of a major "terrorist operation" on its soil ahead of the concert hall massacre near Moscow last month, three sources familiar with the matter said, Reuters reports.
In the deadliest attack inside Russia in 20 years, gunmen opened fire with automatic weapons at concertgoers on March 22 at the Crocus City Hall, killing at least 144 people in violence claimed by the Islamic State militant group.
It is harder, however, for Russia to dismiss intelligence from diplomatic ally Iran on the attack, which has also raised questions over the effectiveness of Russian security services. Moscow and Tehran, both under Western sanctions, have deepened military and other cooperation during the two-year Ukraine war.
Iran arrested 35 people in January, including a commander of Islamic State's Afghanistan-based branch ISIS-Khorasan (ISIS-K), who it said were linked to twin bombings on Jan. 3 in the city of Kerman that killed nearly 100 people.










