It was Feb. 10 when I wrote the first part of this article. It's been almost a year, but Aleppo didn't receive the attention it urgently deserved. It was one of many pieces I wrote about Syria, the biggest tragedy of the modern age; it was one of millions of articles penned about it. While the number of civilians killed by airstrikes in Syria was growing, we were sitting and watching it on our mobile phones. Warplanes were bombing schools and hospitals, people were starving, hundreds of new refugees were fleeing Aleppo, photos of corpses in bombed-out houses, pictures of children who lost their parents or their limbs, destroyed cities and dying animals… And we did nothing.It was a non-stop nightmare then, and it is worse today. Last month, the Syrian regime, backed by Iran and Russia, launched an all-out offensive against Aleppo, the second biggest city in Syria where millions once lived. The world is watching a tragedy unfold through heart-wrenching videos and recordings posted by civilians under heavy bombardment from the Bashar Assad regime and its allies. It is spine chilling to see people discuss if it is genocide or just a massacre while eating chips and drinking cokes. Syria's nearly six-year-old civil war affects the whole world, starting with neighboring countries like Turkey, and Europe has shown symptoms of being affected next, and no one who cares is prepared to bear responsibility. Instead, they do nothing but watch and tolerate what the U.N. has described as a mass killing of civilians, including children and women and opposition forces.If you pit the people of a country against its army, it's inevitable you will see hundreds of thousands murdered. If the army gets enormous support from other states like Iran and Russia, and you just watch, you can expect nothing but a blood bath. But when you do nothing to stop such evil, it doesn't stay where it started, it spreads and burns others in time. We have seen it in Europe before. The world did nothing to stop General Franco during the Spanish Civil War, Italian fascists led by Benito Mussolini when they invaded Ethiopia, the Kwantung Army of Japan when they attacked Manchuria or Adolf Hitler of Nazi Germany; and the result was World War II. Then U.S. President Franklin D. Roosevelt admitted that the policy toward Spain was a grave mistake, but it was easy to be wise after the event.It's easy to lament the dead after the fact, to remember millions who lost their lives and say "never again" after all the horses have bolted. It's comfortable to sing songs about tragedies, pen novels, and give medals of Honor; but we need leaders that have the guts to stop them when or before it happens. The lyrics of a song by the Manic Street Preachers, a Welsh alternative rock band, recently comes to my mind, "If you tolerate this, then your children will be next," when I look at photos from Aleppo. The song was inspired by the Spanish Civil War and takes its name from a Republican poster of the time, displaying a drawing of a child killed by the Franco regime under a sky of bombers with a warning written at the bottom: "If you tolerate this, your children will be next."The Spanish Civil War was the biggest proxy war of its time, while many young men outside of Spain joined International Brigades and fought side by side with the Republican forces against Franco's Nationalists. In the Syrian case, the outcome is similar: The opposition fighters have supporting manpower, but they have become "jihadists" or "radicals." The line of the song, "If I can shoot rabbits/then I can shoot fascists" was originally quoted in Hywel Francis' book "Miners against Fascism" and attributed to a remark by a man who signed up with the Republicans made to his brother. It is a pure example of a young person who becomes self-radicalized when he watches people being butchered, while the world does nothing. Another example is English novelist George Orwell who stopped writing in 1936 and set out for Spain to join the fight against Fascism. Wounded in the throat by a sniper's bullet while fighting at the front, he later penned his experiences and observations of the Spanish Civil War in his book "Homage to Catalonia." He got into many difficulties when he tried to publish it, but today he is one of the most admired and inspiring writers in the world. Another example is the bombing of the small Basque town of Guernica in 1937 by Nazi Germany's warplanes that backed the Franco regime, inspiring one of the most famous paintings in the world, "Guernica," by the immortal Spanish painter Pablo Picasso.The atrocities that marked the Spanish Civil War triggered young people to do something while the whole world watched, paving the way for them to be radicalized and inspiring art afterward. The Syrian Civil War in the Middle East, a much longer version of the Spanish Civil War, will inspire artists of the future when the time comes just like it unfortunately radicalizes the youth of our times. They will paint the bombing of Aleppo. They will sing songs about freedom fighters. They will write novels about the people's suffering and heroic resistance. But it will be too late. Hundreds of children killed by heavy bombardment will not be here. And because we tolerated this, I fear other children will be next.