Russia today called on Washington to thoroughly investigate a coalition strike that killed at least 62 Syrian troops. Moscow said it is deeply concerned about what happened. <br/><br/>The US admitted the coalition strike on regime positions near Deir Ezzor expressing regret over the loss of life and said it was a mistake. <br/><br/>Moscow, however, said it suspected foul play aimed at disrupting the next stage of the ceasefire agreement which would see the US and Russia establishing closer operational coordination in Syria.<br/><br/>The ceasefire came into effect on Monday, and if it lasts seven days, Russia and the United States are to work together to target the extremist Islamic State and Al-Nusra front.