The investigatory experimentation of the crash of the Russian Tu-154 passenger aircraft operated by the Russian Sibir airlines, into the Black Sea, has proved that the aircraft was shot down by the S-200 anti-aircraft missile launched during the Ukrainian Air Defence exercise, which took place on the cape Opuk in the Crimea on October 4. Yevgeni Marchuk, the Secretary of the Ukrainian National Security Council, had to admit this fact once again. "There are no other versions left," he stressed on Friday speaking about the results of activities performed by the Russo-Ukrainian commission and of the experimentation, which recovered the second-by-second chronology of the crash, which claimed 77 lives of passengers and crewmen of the jet. The tragedy was simulated by means of the S-200 anti-aircraft missile systems, computers and the MiG-29 fighter used as a target. At the same time, Yevgeny Marchuk left unclear another issue: why the Ukrainians have launched combat anti-aircraft missiles in the zone with busy air routes? Air traffic was the very reason why the Soviet command banned all missile launches in this area. The Russian commission consisting of more than 20 experts, has submitted the results of its activities to the Ukrainian side in the Crimea. Ukraine has accepted the obligation to finish the investigation and pay the damages. But Kiev's determination to do the latter is doubtful. Ukraine could be hardly considered an example of strict fulfilment of its finance obligations and agreements.