-Analysis- BEIRUT — The terror attack on a Moscow concert hall last month killed 145 people and wounded more than 500 in the deadliest assault in Russia in many years, after armed gunmen open fire on concertgoers at the Crocus City Hall on the western outskirts of Moscow. The aftermath of the March 22 attack raised many questions and fueled various conspiracy theories. Much was made about President Vladimir Putin’s accusation that Ukraine was somehow involved. Yet all objective signs point to the responsibility falling on the regional faction of the Islamic State, ISIS-Khorasan, or ISIS-K, the…