The mechanism would be used even to routinely shut down the reactor after the experiment for the planned maintenance and the scram likely preceded the sharp increase in power. However, the precise reason why the button was pressed when it was is not certain, as only the deceased Akimov and Toptunov partook in that decision, though the atmosphere in the control room was calm at that moment. Meanwhile, the RBMK designers claim that the button had to have been pressed only after the reactor already began to self-destruct.