The downing of the Malaysia Airlines jet in eastern Ukraine deserves the strongest condemnation because the calamity, as Ukraine President Petro Poroshenko put it, is not an incident but a “terrorist act” which targeted innocent civilians.

The tragic incident, which killed all 298 people aboard, especially touches the hearts of Koreans because it reminds them of the Korean Air passenger plane that was destroyed by a missile fired by a then Soviet Union fighter jet over Sakhalin in 1983. All 269 people aboard perished.

The incident prompted the International Civil Aviation Organization to prohibit attacks on civil aircraft even if there has been an airspace violation. It is sad that the tragic incident 31 years ago did not give any lesson on humanity.

It was truly horrible to see the scenes of the crash site on television, with human bodies and fragments, baggage and wreckage sprawling over vast fields spread out on farmland and villages.

What is incomprehensible is that the pro-Russian rebels controlling the crash site have been tampering with evidence as well as blocking international rescue workers and investigators’ access.

Television footage showed that the Ukraine separatists moved bodies into refrigerated train cars and even using cranes to remove big pieces of what remains of the Boeing 777 jet. As Australian Prime Minister Tony Abbot said, the site is being treated more like a “garden clean-up” than a forensic investigation.

Evidence and circumstances are growing that the catastrophe was perpetrated by Ukraine separatist rebels supported by Russia. The rebels are believed to have shot down the plane with a Russian surface-to-air missile.

As things stand, the world, more specifically the United Nations and the West, must act quickly to step up the pressure on Putin. As the resolution adopted by the U.N. Security Council demanded, the most urgent thing is for the rebels to allow full international access to the site to recover bodies and conduct the investigation. Putin must not waste time and take follow-up actions immediately.

The root cause of the mass disaster is the conflict between Russia and Ukraine, which started when Putin annexed Crimea and fanned separatist movement in its former fellow republic of the Soviet Union era. The air disaster commands the international community to expedite its efforts to end the conflict that threatens world peace.