In the latest escalation of tensions between US and Russia, the Kremlin has squarely blamed the US for the deadly attack on Crimea which was carried out using US-supplied ATACMS missiles. At least four people were killed and 151 were injured in the attack, and Moscow has formally warned the US that a retaliation would follow. WION's Shivan Chanana discusses with Glenn Diesen, Professor of International Relations, University of South-Eastern Norway.