Russia on Friday (May 24) said that Islamic State executed the March concert hall attack in Moscow in coordination with unnamed entities in Ukraine. The terror attack which killed over 140 people was the deadliest attack on civilians in Russia in two decades.

Russia says Ukraine gave refuge to fleeing Islamic State terrorists after Moscow concert attack

Iran had 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.

Iran alerted Russia about security threat before Moscow concert hall terror attack

It has been a consequential week for Moscow by all counts. The week began with President Vladimir Putin securing an unprecedented fifth presidential tenure in Moscow's corridors of power, surpassing Joseph Stalin.

The Capitals: Moscow hit by worst terrorist attack in decades; Delhi's anti-corruption reckoning; and more